I get cravings for various foods/meals I’ve had before that have nothing to do with being deficient in vitamins or amino acids.
For example, I’m quite certain the cornmeal pancakes my dad would make don’t contain any vital nutrients not satisfied by my current diet. But I occasionally get cravings for them anyway.
Furthermore, when someone gets hungry it’s normal for their minds to start thinking of foods they liked, and lots of people were probably raised on meat heavy diets. So when they get hungry or nostalgic for food their mind will likely think about non-vegetarian food.
Maybe that will go away if they find a wide selection of vegetarian foods they like, but again I doubt that’s the case for everyone, and it definitely won’t overwrite any childhood memories of favorite foods/meals.