It's a chicken and egg situation: did journalists become more adversarial because politicians became more evasive or vice versa?
I don't know the answer, and maybe it's just that tv shows have changed and they have to have 7 segments in a half hour show rather than 1 or 2 because people's attention spans are shorter.
https://youtu.be/s_vTwHq1his here's the video of Rory Stewart on GMB, I don't know if I'm being biased because I like him but I thought he was trying to answer the questions and not be evasive, although when you express a complex thought you sometimes need more than one sentence to do that, and they kept interrupting him.
Anyway I think we do need public service broadcasting and to say that people can make their own minds up whether a politician is telling the truth is like saying people use fact checking websites - ie to be extremely optimistic about human nature.
The fact is that there are some politicians devious enough to launch a full scale assault on the truth (Trump for example is still talking about total exoneration) and they need to be robustly challenged.