why does he take your pass when you come in, does everyone in una do this as well? do they just have an infinite amount except for you? or do they have an infinite use pass that you just don't have access to
Yes. Fawn eventually tells you there's at least 2 types of passes. The one-time use passes the player is faking, and the incredibly difficult to obtain "permanent resident" passes like her family has.
From a lore perspective, I imagine there's also work visa type passes too, that will let you in repeatedly, but only for a job, and don't grant residency.