You already can. The veggies ones have big “veggie” letters on them.
No, not always. The OP photo is a good example of this, it doesn't have any word starting with "veg" on the front. What clues there are are white text on a light colour background or vice versa, meanwhile the "meat words" are black text. The meat words are visually promoted, while the vegetarian stuff is drawn in such a way as to encourage you to miss it.
I’m not talking about ready-made meals or other meal types. I’m talking about “raw products”. Things like “meatballs with cheese” are not a raw product and you won’t find them in the meat fridge, they’ll be with the frozen meals section
That's kind of what I was getting at, raw cheese is probably the main concern (because cheese itself is something that has to go off in a controlled way). Also, I do know supermarkets that sell raw meatballs with cheese in them in the fridge section. They're really good, although best eaten soon after purchase...
I don't think there is actually any regulation (yet) that would stop a shop from putting meat products next to meat substitute products. Eg, putting meat free burgers in a burger section. And I don't think there should be.
If you do know of an actual regulation, rather than just assuming there is one, I'd like to see it.