Agreed 100%, and some of the "simple" approaches like repetition penalty, can harm output, because for example markdown tables repeat a lot of characters, and if you just blindly apply repeat penalty, it will just stop doing what you've asked for.

My guess is that they have some kind of state-aware sampler, and they know if they are in the table, etc. Because then you can sample in a much better way. Just like with grammars, but grammar itself is probably not enough.

Sampling and tokenization are IMHO the biggest open problems. We have something which kind of works but it's nowhere close to be perfect.