Not everywhere in the world uses the same concrete walls. It's quite common to see dozens of access points trying to share the same three 20MHz channels available at 2.4GHz in places like the US or dense areas in Asia.
I live in the US and I just counted 65 visible APs on 5GHz. The DFS channels aren't usable in this area, so almost all of those are trying to share the same 2 80MHz channels.