In a feudalistic dictatorship the criteria for the legitimate exercise of power are very basic: don't lose big wars (national honour), don't let the people starve (survival). That's about it. So legitimate governance is rather easy (although for the same reasons, good governance, which requires more effort, will be rare indeed). But consider the unfortunate politicians in a liberal democracy. Liberal societies expect much more from them (e.g. health care for all) and delegate more power to do so (e.g. in the form of taxes: 40-60% of GDP spending across the OECD). But that power is massively constrained.
Liberal politicians are supposed to make choices on behalf of the public interest and society's collective moral values while meeting tremendously high standards for legitimacy that make such decisions difficult, divisive and exhausting! Everyone is crying out about not being properly heard; that the constitution really means x, or the opposite; that such and such must be done, NOW; that marriage should mean one thing, or another; that building a nuclear power station in their town is an outrageous injustice .....and on and on. No matter how honestly and openly democratic politicians try to make decisions of any importance, huge numbers of people will completely despise them and question their legitimacy (and integrity, intelligence, and sanity). Unsurprisingly, politicians don't want to take on the challenging and thankless responsibility of making those bitterly contested choices, even though that is supposed to be their job.
The result is a flight from responsibility and the consequences can be found in the political sclerosis and vacuity pervasive in liberal democracies. Politicians dodge even trying to make difficult decisions that might upset some people by refusing to make any. Some countries are worse than others - Greece's politicians (until recently) seemed to have done hardly anything in 30 years except organise the Olympics - but all are at least partially guilty of avoidance behaviours. The main forms of avoidance behaviours are the transfer of power to other domains without real authority; and the transfer of authority without power to procedures. In their rightful place, these are good things - we would call them liberalism and the rule of law - but when they are employed to escape political responsibility they become vices.
Liberal societies make extensive demands on their politics and so tend to transfer quite a lot of power to them. However, in contrast to the stereotype, democratic politicians often appear as anxious to transfer power away from themselves as the people are to give it to them. They like to outsource difficult choices to other groups. Economic management, employment, and health-care can go to the market ('neo-liberalism', in so far as it really exists, may be as much a convenient way for politicians to avoid making difficult decisions as evidence of their ideological faith in markets); values and ethics can be managed by religious and ethnic groups (under 'multi-culturalism'); controversial legal issues like abortion can be farmed out to judges; etc. Not surprisingly these non-governmental bodies appreciate the gift of power. Also unsurprisingly, most of us think something is wrong in having such important issues decided by democratically unaccountable bodies.
The trouble is that these other actors come to have power without legitimate authority, while the politicians retain legitimacy by avoiding making any use of it. And no-one has responsibility.
Politicians also like to transfer authority to procedures managed by bureaucracies. So instead of them having to make difficult choices - with winners and losers - some technocratic procedure is allowed to take over most of the process of proposing, evaluating, and implementing policies. For example the consumer-price-indexing of welfare payments - based on technical criteria and assumptions about what constitutes destitution - is allowed to replace political decisions, and debate, about what society owes its poor.
Such procedures may be good tools for governance, but they are poor masters because they have inherent biases which they are themselves unable to consider. It's like asking a hammer how one should put up a bookshelf. Take a random example from the UK. The owner of Heathrow airport wants permission to expand to increase passenger-turnover. Some transport sub-committee undertakes to write a technical report on future air-transport needs for Britain. The cost-benefit analysis indicates that an extra runway at Heathrow will increase aggregate social welfare. Of course it does. What counts as a cost or benefit depends almost entirely on how easily it can be measured within the framework, and passengers (even imagined future ones) are much easier to count than 'site of natural beauty'. A planning process begins and grinds along to its inevitable conclusion. Lots of people are very upset, but who can they really complain to? The politicians deliberately gave away their authority to the procedures, and the bureaucrats themselves lack the power to do anything but run through those procedures no matter how ridiculous the final outcomes.
Again, neither the politicians nor the bureaucrats are responsible.
When democratic politicians stop trying to live up to the responsibilities of their jobs, and we the people stop insisting that they do and supporting them in their efforts, it is not surprising that they stop taking themselves seriously. Hence the vacuity of so much present politics: are 'dangerous' dogs and cigarettes really so important that our politicians have to act on them right now, while fundamental issues of ethnic integration, the ageing workforce, rising inequality, etc are indefinitely fudged and delegated elsewhere? Or are they just easy, in comparison to the hard choices we won't let politicians make anymore?
But those hard choices don't go away just because liberal politics prefers to avoid them. That is why the perceived failure of liberal politics is so dangerous. For if we cannot get anything important done in accordance with our liberal beliefs about legitimacy, that undermines those beliefs absolutely and opens the door to alternatives. And there is no shortage of would-be politicians with the skill of identifying and exploiting society's fault-lines and with strong ideas about what should be done about 'the problem of immigrants', etc. Such politicians and their followers have no stomach for the tortuous consensus building processes of legitimate political decision-making - they only care about doing things their way. But they don't need to, because it is liberals themselves who have shown that such standards as fairness, public deliberation, and civility just get in the way of getting anything done. When liberal politicians stop working so does liberal politics, and the crazies may win by default.