They could offer a deal to Toyota and tell them they're offering image-only ad space on all car-related pages. For example images with deals. Toyota would know from the referrer that the click came from Wikipedia.
All the other images are hosted by Wikipedia themselves and are not ad-related, so I don't see where's the issue here.
I'm just saying that the domain that hosts the page and the domain that hosts the image are often not the same. Wikipedia hosts the articles, wikimedia hosts the images.
If a browser wants to be strict about what it loads, most of the web would appear broken. Maybe google could have the weight to force such change, but no way could mozilla impose such a strict rule.
All the other images are hosted by Wikipedia themselves and are not ad-related, so I don't see where's the issue here.