I think in some countries people understand all these issues and some do change their behavior, but it takes much longer than you would assume (reference: https://ourworldindata.org/grapher/per-capita-meat-consumpti... - note the peak consumption is in the past).

On the other hand you might downplay how bad can be for some people to totally eliminating meat/dairy. I know a couple of examples that had big issues with iron deficiency due to that. Pills didn't work for years, while restarting eating for a couple of months meat fixed all their health issues.

I do agree though that people eat way more than they need, but probably it is not only meat related (also sugar, carbs and others).