I’ve never heard them complain about the use of cash.
A theatre is used to it, I suppose, but cash handling is still a nuisance. You need some equpiment (a cash box, at the very least), (more) reliable employees, it needs to be counted and deposited, and still can get stolen.
Cinema’s work the same way. Normally extra tickets are sold at the counter as well.
Sure, but they have generally a cut-off time. If you don’t pick up your reserved tickets 30 mins or so before the show starts, they’re going to sell them anyway. Perhaps not what you’d want with a seminar.
You could go for a full reservation system, but costs might be too high if it’s a small seminar.
I agree, just pointing out why reservation only might not be the best solution.