Vegetables do have it, and other pesticides too. But depending on the crop, the application is different, and often stopped (or nearly stopped) by the skin. Leafy vegetables have no such protection, hence why they are almost universally "dirty." Depending on the type and amount, pesticides can and do penetrate the skin, like that of an Apple.

Wheat is a little more special, because it is the most important crop of humankind, full stop. It is also protected by a shell, which gives the false sense of safety. Nuts too contain impressive amounts of pesticides because of the ubiquitous application, and the same perceived sense of safety. However, both nuts, wheat, and other grains hold on to pesticide very well.

If you were asking about gluten allergy specifically, I don't think that's about pesticides at all. At least I just don't see a convincing evidence. Though that doesn't mean pesticides can't interfere with the mechanism. Like practically all things with our food, we simply don't know the answer.

> even meat?

Pesticides are present in meat, though they are in lesser quantities iirc. We have laws against antibiotic use in farming for a reason, they too contaminate meat very easily. Though, at least with antibiotics, if you cook the meat for 45 minutes, their bactericide effect is almost completely broken down. I say almost, because that, we also don't know. The best research that I know was conducted by Iran, so take that with a grain of salt.