You could either set the allowed users per account (shared-users) to 1 so they can't share, or just set a bandwidth queue on the interface so all users will share that one queue. See the manual for setting a single queue for an interface (there are also many examples in the forum on how to do this).
Perhaps you are missing some of the features of a hotspot under a hotspot user profile. If you define your own profiles, each time a user logs in, a dynamic bandwidth queue will be created for them, so you shouldn't need to create these manually. The default profile does not define bandwidth limitations, so you aren't getting the dynamic bandwidth queues that are created automatically when a user logs in if a bandwidth limit is defined. Take a look at the hotspot and user profile sections from the hotspot manual.