I've only ever been to one public range, but went there fairly regularly for a couple years. It was an outdoor range, and they wouldn't allow more than two shooters per lane, and that was ofc provided they were an actual "party," not just two random people. Even if you came with more than one person, only two allowed at the firing line at a time (and only one shooting, ofc). Anyone crowding your lane uninvited at a shooting range ought to be addressed swiftly and without room for confusion, IMO.
If insufficient shooter space (narrow lanes) is the reason, that range has serious design flaws and I'd find somewhere else to shoot.