Never listen to pet shop advice
I saw a pet store house 4 adults in a 55 gallon, but that doesn't mean it's right or should be done.
I've also seen petstores house babies on sand, the one I was in yesterday had a baby beardie with a red light and nothing else in the middle of the day, I went back today to exchange something and he still only had a red light and the cage he was in had 3 black walls and the glass front so it was really dark and I asked the employee if he ever gets any other light and he told me no, he only needs the red heat lamp. I actually don't know if I've ever seen a petstore have UVB on their babies. Even some of the petsmarts around me don't use UVB, but 2 do.
I had one petstop try to sell me 3 babies and told me I couldn't buy just one because he would get lonely depressed and eventually die. Another guy told me if I bought 2 (they were brother and sister) that they would never mate and if by chance they did I could just sell the babies or bring them in and they would sell them.
There are the few that know what their talking about to some extent, but majority don't.