I actually consulted briefly with a company that tried to do what Qwest is doing.

Popular bars and clubs have lines out front for a variety of reasons. It exists, and while "we're at capacity" is one reason, its not the only reason.

The issue they encountered was that right now, "skipping the line" is something you pay the bouncer to do in cash. They're also the ones you have to convince to use this app. But you're asking them to use an app that kills that revenue stream for them, it transfers all that $ to the club owner instead. So bouncers would only half use it, or "forget" to use it, or quit and go to another club.