How do they jack up big coach when replacing tires?

My tire place uses huge floor jacks. One corner at a time. For oil changes at home, I use levelers and place jack stands under front axle for extra safety. That being said, has anyone used a bumper jack before? All we had a few decades ago. I've seen more than a few cars fall off of those and none off of levelers or bottle jacks. I'd think that a hydraulic line would have to blow completely at once to cause a rapid fall. A leak would cause a slow drop. Still, better safe than sorry.