I'm sorry to hear about your experiences, but I don't think some huge bureaucratic red tape will be any better. What will happen is that all the toxic assholes who will rant, make creepy remarks, etc. won't be told to buzz off, because doing the whole third party auditing will be too much effort and costly.
And I also think it's fine to exclude people for subjective reasons, even if it's (marginally) "tax-funded". If you go to the JS meetup and keep complaining about how bad JS is then maybe it's best that you stop coming. Generally very contrarian and combative? Maybe it's best those people also stop coming.
People that go to Sunday mass to proselytize that God doesn't exist (or to an atheist meetup to proselytize that God does exist) are also not welcome. Saying "it's tax-funded, and therefore it should be open to all" would lead to absurdity.
In the end we have to accept that not everything is perfect, and that trying to achieve 100% fairness typically makes things worse.