Wikipedians are the ones who provide Wikipedia with their images, so most likely, yes, your assumption that people are taking pictures of these at home and then uploading them onto Wikipedia are most likely correct because A) No copyright issues and B) It is pretty much easy and free now-a-days.
Unlike some other sites, it is actually very easy to upload an image onto Wikipedia, although getting it to stay on the site is another story. Anyways, yes, people are probably taking those pictures at their houses.
Hope this helps :D
Own experience and opinion as a Wikipedian for 2 years.