Yeah ... never thought about it before, two years old was the biologically determined standard. I was the oldest of three and remember helping my Mom with my brother who was born in 1970. He had big soft cotton diapers and they got opened over the toilet or just thrown directly into the covered plastic bin/hamper with a couple gallons of bleach water in it. I'm afraid to ask, but here goes:
*So, what age are kids getting potty trained at these days?

Anything past 2½ makes me wonder, how the hell can convenient diapers possibly compete with desirable benefit of not having to walk around with shit in your shorts? Stinky, sticky actual shit? Is this not viscerally unpleasant to all?
I wasn't in diapers at 2½, that's when my sister was born and because she and Mom were napping all the time I made my own entertainment. I decided to go visit my Dad at the hospital where he worked. I knew where it was, only a mile away. I had the nurses page "Dr. Daddy" from "Rappelling_Rapunzel". Luckily my name was unusual back then, and he thought he might come down and check just in case. Apparently I sitting on the counter at the front desk getting candy and attention from the nurses when my Dad got off the elevator just as Mom was coming through the front entrance with a couple of cops. I can't imagine waddling a whole mile with lumpy diapers. People would have noticed me even though I trotted with purpose, and knew how to wait for the traffic lights.