Carrying your own offspring is not the same as being employed to carry weight all day (and not necessarily because you really like that profession.) The regulation is in place to protect the worker, be it from the employer or those who don't know any better from themselves.
But 50lbs is pretty light. If you're in reasonable shape moving objects of that weight every day should be fine. It's only (approximately) one big Olympic plate.
That's not just some thing they happen to do once a day. Its what they do ALL day, in addition to many other things. The purpose of the exoskeleton isn't really to increase how much you can lift. Its to make it so it is less tiring.
