OP - you know your proposition isn't true. Solicitor here. Not a barrister, 2:1 from Oxford. You would hate me because of all this and because I was sporty at uni, several academic articles published, fluency in a second language, socialised seamlessly with some very socially privileged people and did a Masters degree at an elite Continental university.
But I came from a frankly dreadful school in Scotland (headmaster: "I don't expect any of the pupils from this school to go onto university", argued with the careers advisor who tried very strongly to dissuade me from applying for law and Oxford). Some of us just do come out naturally determined, clever and with not the slightest shred of self doubt or fear, even when a shy 17/18 year old.
There are so many people who are scared to leave their comfort zone and put the effort in. Those who reach Oxbridge are in some way self-selecting because they already have a lot of the other attributes needed. Now, I know all about the arguments about private schools making pupils more confident, but that still doesn't guarantee them Oxbridge and a pupillage. If you share the attributes and really work hard, you can make it. Even now.
There is good reason the bar is so elite. And thank goodness for that. I made the decision to go back to Scotland for the countryside and eventually realised that its just as hard to commute into Edinburgh city centre as London. But the legal profession in Scotland is relatively small and not that well educated. All over the world, its standard for even solicitors to do at least masters degrees before practising; not so in Scotland. It must be the only jurisdiction in Europe where doing something slightly academic before qualifying is considered a negative trait for a lawyer. In order to gain work as a solicitor there, I had to dumb down my knowledge in order not to scare the senior partners. Even so, I still used to have to put up with a certain level of negative comments about it. Perhaps there are a couple of firms where that is not the case but it is mostly so. We all know that an academic background translates well into court work; this isn't considered in Scotland.
Becoming an advocate would have probably been a better choice, even so there are some thick advocates around. A number of them mistake themselves for being brighter than they actually are. You just cannot fill in the gap that postgraduate education at a top university provides with a career spent entirely in a tiny jurisdiction practising in one city all your life. It just didn't appeal.
I probably should have become a barrister, but tbh, the financial rewards aren't guaranteed enough to make it worth my while. I now don't practice at all and run a related business which has earned me at least as much, if not more, than being a semi-successful barrister in EandW. If I go back to practice, I will do so in the European jurisdiction that I did my Masters in, if thats still possible after Brexit. Perhaps Wouters will assume some relevance after all.
Incidentally, there are always ways and means. It currently costs 2000 euros to do my Masters, and the continental universities give students much more access, including socially, to judges. I met judges at the CJEU socially all the time during my time there. There are a lot of conferences and dinners afterwards where its really easy to make useful contacts, as long as you can hold a conversation. That makes getting references much easier. And yes, you do need to involve yourself in moots and student societies or organisational committees - you demonstrate the skills that you will need in places like the Bar by doing so. OTOH if you stay at home to go to your local university, do nothing outside studying at uni, and then expect to present yourself as a candidate for the Bar, you are likely to be unsuccessful. But even getting into do a Masters at Oxbridge is far easier than getting admitted as an undergraduate.
But thank goodness the Bar is elite and the standard of candidates is incredible. There are so many thick lawyers around who have become de-skilled, who prevent other people, often women, from reaching the positions they block. Thank goodness there is somewhere where brilliant, motivated, people can go to have a career that is considered elite.