I've used public transit for the better part of 50 years, including inner-city buses and light rail trains in several cities. And I've literally never, ever seen nor felt nor smelled an actual "puddle of urine" on a seat. Yeah, sometimes the seats were kinda iffy or damp; perhaps someone spilled a drink there. There were often people eating, or even drinking a beer on board a bus. So I often see pistachio shells or a discarded bottle/can behind a seat. But human waste is unheard-of.

But any actual urine "spills" would've gotten cleaned up right quick. They simply don't tolerate that stuff. Look at any bus operator and they are tough as nails if someone tries shenanigans.

In fact, the craziest times I've had were in ride shares and taxis. I was all dressed up for a funeral one morning, summoned a taxi, and the driver who tried to pick me up was obviously drunk. Another time, I had a medical transport that was summoned, sat at some gas station for 15+ minutes, and when he arrived at my place and I got in the back seat, it was wet and had clearly been through a hasty cleanup, and I could smell urine permeating the vehicle, and it was absolutely nuts, but I said nothing, because it probably wasn't the driver's fault. Probably.