Some movie also have a very small pic taken from the trailer or from another site, in this case it can be replaced when the movie page is completed.

I do not do that very often - last time I changed the pic, on which was just rera part of the vehicle for the one, few shots earlier with whole car on it.

Guess you have to trust the admins to do their best for the site. I don't have a problem with that. The clearer the pictures the better the site as a reference for other visitors.

I have the same feeling about the pictures I add, but on the other hand when I can put better pictures I'd like to do it.
When the one that put the pictures is known I usually do not replace these pictures, except those that are really better.
A "better" picture would be for me a bigger and/or sharpen picture. Or where the vehicle is more visible.
If it is the choice of the view of the car that could be better in my opinion, I add extra picture in the thumbnails with other views.

All admins can remove/exchange existing pictures. I'm not sure I like it when pictures I worked with are removed in favour of other pictures ... I mean, what is a good picture? That is a very personal opinion.