Everytime I'm on a foreign airline, I notice how FA's don't get all bent out of shape if I need to go to the bathroom while the seatbelt sign is on. At most, they advise me politely that it could be dangerous, and that I would have myself to blame if I was injured because of turbulence.
Fine, I don't mind being treated like a grown-up. I like to be able to decide whether a slight risk of injury is more or less important than the need to go, and now.
Compare that with my numerous experiences on various domestic airlines where, after being stuck on the tarmac for an hour +, 34th in line for departure and we're not moving, I'm still being chased by the FA when I finally make a break for the toilet.
I don't think the FAA is more concerned with our welfare than their foreign counterparts. I just think the airlines want to avoid any possible excuse for a lawsuit. I wonder if anyone has ever sued an airline for a burst bladder...