Wait to be seated
"Someone will be with you in a moment."
"Sorry that took so long."
"I can't seat you until your entire party is here…"
"Oh, but you can't wait in the entrance…"
"Or at that table by the door."
"Actually, management says I can't serve any drinks until you're seated."
"So you're all here? Great. I'll start getting a group of tables together. It'll be about 10 or 15 minutes."
The question isn't whether the customer is right or wrong. It's morphed into: How many rules will a customer deal with before she stops being your customer?
For niche markets, lots of rules are good. They're almost expected. (As long as they're widely accepted and understood by the community you're working with.)
However, for a local cafe, rules just get in between me and a stack of pancakes.