How about "How many shops have DROPPED a truck off of a lift?"
I know of one. They dropped my girlfriend's '95 Chevy 4x4 Extended Cab pickup off of a lift in '97, while they were replacing a water pump under warranty. It messed the truck up pretty good, but it was still repairable.
However, she sued the shop for damages to her truck and recovered enough to buy a new truck and simply traded the damaged one in, as is.
It's extra parking for vehicles that might have to stay outside for the night. I often had my shop completely full overnight and cars out in the lock up yard too...the yard often got broken into at night,the cars are better off inside. I've never had a vehicle fall from a hoist,but have seen it once.
We don't leave anything decient outside at night. I often leave cars in the air on the lift especially if I need more room.
I don't ever lift a car if there is any chance of it falling off the lift. And if an Earthquake knocks it off the lift that will be the least of my problems.
The feet of my lift are up to code. Mounted into the 6 inch thick concrete floor.
Since my trucks weigh 9200 pounds many lifts don't have the stones for them.
I left one outside at a local trans shop one time as we needed parts and had to wait for a case hardened piece instead of a stocker. Would have been tough to steal anything 7 feet in the air!
I've just left one up semi tonight - it's our field service vehicle (Mazda Bounty),and is very rear end heavy with all the tools and gear on,so have got the rear wheels on the ground while waiting for front brake parts. If I left that fully up overnight I'd have to put support stands under the rear.
Yes we leave them up, why not? If its safe to work under its safe enough overnight.
And yes I have had a mechanic drop a full size school bus off a lift,You need a huge wrecker and giant sling to fix that.
Story for another day is when I worked on vans at a dealer and a guy dropped one off the hoist next to mine wich took off the door of the van wich I had my body halfway in seconds earlier.