In reply to Martin W:
> they can't come out and say: "This just goes to show that we should never trust the public with voting on important issues that they don't really understand," without fundamentally weakening the legitimacy of their own role in the legislature (at least amongst people who don't understand the principle of representative democracy).
True that they can't say that, although not sure it would weaken their position (if you assume they're right) - it would just make it harder for them to get elected again!
And although the OP may complain, actually you NEED professional politicians if you want decisions made that balance the 'will of the people' with expert advice, technical knowledge, financial implications, and the whole host of other things that (should) go through the minds of every serious politician every time they vote. Someone said above that they're not an 'industry'. Well that's true, but their business/job/calling/whatever you want to term it, is decision-making. Want good decisions made? Employ people who do nothing else.
I'm biased as have worked in Parliament, but the problem most definitely is NOT professional politicians (most of whom actually have significant experience across a variety of fields, rather than no experience -which obviously people prefer to believe). The problem is bipartisanism (eg Cons cutting 'Short' money so that opposition parties get fewer resources and less cash); vicious party discipline and whipping (see recent reports on threats made to Con Remainers); dodgy media which is never held to account (IPSO totally toothless as reg body); dogmatic interest groups (Momentum agitating for weird Militant rules from the 70s devouring Labour's attempts at Opposition); and the (resultant) dearth of issue-based politics.
But sure, it's all because none of them ever worked in a Greggs or picked up a hammer before going to uni.