The role of humidity is BSOD and other glitches
Hearing aids are the proverbial ten pounds of crap in a five pound bag; lots of electronics in a tiny package. The enclosure, being plastic or silicone, doesn't absorb moisture. It is placed in a crevice on the human body. As the user sweats, moisture will start to accumulate, and cause the problems mentioned. 

This is not the case for the handheld devices mentioned. Their normal use case puts them in the user's hand. If they are not in the user's hand, they are in a case, pocket, on a desk, etc. Excessive sweat will only be a problem when it gets to the point where the device is physically wet. Your average glitch in these types of devices is much more likely to be the result of a software problem.

Moisture in the air is not going to cause problems for either device.