I keep a USB condom, or data-only female-to-male adapter, in my tech bag for this reason. The adapter is also transparent to make it "clear" that data wires don't exist on it.
Are there any decent reports of someone's phone getting compromised this way?
Not that I know of, but, regardless, USB was a mistake from the beginning.
I have a USB power meter that also acts like a data diode. I like it a lot, it can shows graphs of current draw.
Is this really that hard to deal with? Just do a daily check on them or install some sensors.