When I worked at Six Flags-Astroworld, I operated the French Taxis. There was a big sign overhead that said "at least 2 riders per car". So about once every ten minutes, we'd ask the next person in line "How many?" and they would say "one". We'd point to the sign and half the time, the kid would burst into tears or a parent would start berating us for, no lie, ruining their kid's vacation with our unreasonable rules.
Sometimes the kids would insist they were at the park all alone (yeah, right) and HAD to ride all alone and we'd say, "Okay, then you can ride with this kid behind you who looks almost exactly like you" and they would give up the lie and ride with their brother after all.
If we'd let kids ride alone, I would still be funneling them through the gate to this day. Arg. I switched to the Gravity House soon after, which made me stagger out of the building after a full shift, but at least I didn't have to deal with crazy parents.
(Then why on earth have I gone into education--where I have to deal with crazy parents?)