Yes, they can be hazardous for sure. On the farm we still use self unloading wagons into an ag bagger for haylage and silage. So you are often standing between the tractor and wagon with the pto shaft spinning engaging and disengage the wagons drive until the feed table is cleared out, then the apron chain is engaged and the speed is set. Until a large clump comes over the beaters and you have to hustle to prevent clogging or stalling something.
So 2 pto shafts and the wagon one's are connected and disconnected frequently during the course of a day.
I think the newest wagon is 20 years old the others are up to 40.
My favorite tractor end pto guards are the larger flip up ones that will flip up out of the way to get those heavy pto shafts and couplers in.
The fender mount pto switches come in real handy, you really miss them when you are using one of the older tractors and have to climb 2-3 steps up onto the platform to reach the pto and flip it on or off, lots of moving and twisting and turning in a small area.
And then the bagger keeps moving forward as the bag is filled, so up on the unloading tractor to keep the discharge chute were it needs to be, about a foot of back and forth play to maintain.
Those 100+ hp rated pto's get pretty substantial.
I won't say that we get lax but we certainly avoid floppy clothes and especially for me the hair isn't an issue.