Weddings in particular seem to have evolved "check your phone at the door" policies. Though perhaps mostly to keep folks from ruining the professional photographers shots by constantly diving into the action with cameraphones/flashes blazing...
I’ve been to several wedding ceremonies of somewhat large size where no one took their phones out, and certainly not for photos.
Did trust in society hit a new low while I wasn’t looking?
No, no, no. A device in a (near-)stranger’s unsupervised physical possession for hours is a compromised device. No.
But at the same time this sort of thing would also make me kinda annoyed (as I have no problem, generally, keeping my phone in my pocket, on silent, when having it out is inappropriate0.
It's unlikely there will be state actors at this wedding or whatever ready to open up your phone and swap out a chip.