Because, we don’t trust them anymore.
For hundreds of years, modern societies have depended on something that is so ubiquitous, so ordinary, that we scarcely ever stop to notice it: trust. The fact that millions of people are able to believe the same things about reality is a remarkable achievement, but one that is more fragile than is often recognised.
The notion that public figures and professionals are basically trustworthy has been integral to the health of representative democracies. After all, the very core of liberal democracy is the idea that a small group of people – politicians – can represent millions of others. If this system is to work, there must be a basic modicum of trust that the small group will act on behalf of the much larger one, at least some of the time. As the past decade has made clear, nothing turns voters against liberalism more rapidly than the appearance of corruption: the suspicion, valid or otherwise, that politicians are exploiting their power for their own private interest. Link