I think it comes down to what you mean by sub par code. If you're talking a mess of bubblesorts and other algorithmic problems, that's probably a prompting issue. If you're talking "I just don't like the style of the code, it looks inelegant" that's not really a prompting issue, models will veer towards common patterns in a way that's hard to avoid with prompts.

Think about it like compiler output. Literally nobody cares if that is well formatted. They just care that they can get fairly performant code without having to write assembly. People still dip to assembly (very very infrequently now) for really fine performance optimizations, but people used to write large programs in it (miserably).