Having your phone on your person while you are in a roller coaster is something that I can understand but it would not be near your face (are there people dumb enough to take selfies while in a roller coaster?).
But bungie jumping and trampoline jumping should not be done whilst you have anything on your person (keys, phone, wallet). You could easily end up hurt even without an airbag.
Most (all?) roller coaster operators require that you have no phone in your pockets before you sit down. It’s not just the risk of an idiot trying to take a selfie, the phone could simply come out of your pocket during the ride.
High speed impact x gorilla glass x crowds = ugly.
I rode 12 different roller coasters this past Monday, not one required empty pockets, however it was an option to store pocket items in a bin on one of them. I'm realizing as I write this you probably mistyped your... I did take a picture of the Lake Erie islands, and one of Sandusky Bay on a coaster, was probably not wise however. It was interesting to see how Cedar Point is using Samsung smartphones phones & GearVR headsets to breath new life into one of it's oldest coasters, by far the coolest VR experience I've tried.
The answer to "Are people dumb enough to take selfies doing X?" is "If there is no (implied) IQ test to get to do X, they will sooner or later."..
It's a sorry state, and as far as trampolines go, I'd consider it find as long as it does not impair your movement or hurt you if you land on the pocket, and it's tight enough to not fall out of the pocket if you were to walk on your hands upside down.
Same for bungie jumping, trampolines etc.
In fact, I wonder if this wouldn't be a problem with any fall, say on ice etc.