River Roch

A day of errands. One of those was to
pop into a pub to try to book a table for dinner on Saturday. I was asked “for how many people?” I said 4.
“Oh sorry, we don’t take bookings for less (sic) than 5 people.”
“Why is that?”
“It’s because most of our tables are for 4 people.”
Two hours later I still can’t work that one out.