The reason they don't is because they know it is real ... they don't have to prove anything.
Plus, if they did put up a picture you would just say, "Oh, sure but that's just the company putting up their own picture, we need all the companies buying it to put a picture up on their web site"
"No, no, we need all the third party companies to take out a full page ad in their local papers with a picture of it"
"No, no they have to put it on television, yeah that's it but, it must be from a third party and during pime time on Tuesday.
"Yeah,that will do it, unless...????
You are just too funny..