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.

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.

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 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.

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.