It’s easier to chalk it up to cars are like mecha- if they aren’t the focal point of the anime, producers are not going to find specialists, so you end up with CG cars and maybe that will be better than okay if the anime is mostly CG (for instance, you probably wouldn’t notice cars being particularly noticeable in Dorohedero).

To some extent if you watch enough anime, you will tend to notice issues with characters playing musical instruments if you play that instrument or with sports techniques when those activities are not the focus of the anime.

Cooking can look terrible when it’s done as a kind of afterthought, which is especially funny because most people are familiar with what food ought to look like. Cars are probably more important to Americans than cooking is, so the cars thing probably is more of an afterthought to anime production in general.