No, it's usually "stock art", available free or near free. often the images come with the template used to set up the OP site.

I would imagine the reason a brand name like "Xanax" appears rather than "Alprazolam" is to come up more often in organic search engine results. You going to search on "Alprazolam"? - probably not. I can't even spell it without pasting it here!

Last month Overture Search Queries:

Alprazolam 25779 (surprised it's that high!)
Xanax 73696