avriette, i understood what you meant. I have often seen GTPs housed together as juveniles or babies.
In pet stores especially. They are just trying to save space, and it IS a money thing for them. Boo to them! *lol*

When we first got our first ball python a year ago, my husband was convinced that if we got another they could live together. I go around and around with him about this, as i insist they all be separated.
It is totally what someone else said about say, dog food, though. I work at a pet store, and one thing that has happened over the years is that people have realized what companies have been putting in dog food...and are now going for better ingredients, which has led to healthier animals, and longer lives.
I think the same thing is with the snakes...people have learned that housing separately is better for husbandry.

I have to say though, that i have been to a few popular zoos, and i honestly can't remember seeing snakes housed together. San Deigo, Santa Barbara, L.A., Portland, and recently to a few in Australia. I don't *Remember* but this was over a few years, and before i was really into snakes. Mostly though, my old photos and my old memory says housed alone
It's harsh on the house space, but totally worth it to have all the snakes...muwah!