The airlines can allow any devices they want to. They just have to test the devices to make sure they don't affect the avionics. There is really no way bluetooth or wifi back in the cattle car can affect anything in the cockpit anyway. I've tested lots of devices including GPS for smaller aircraft, where the critters are almost touching you, and never found a problem. There are some aircraft in which cell phones turned on in the baggage compartment can give false baggage fire alerts, though, and that's a serious problem. When that light goes on, you have to land immediately to check it, and an immediate landing may not be convenient.

The airlines that don't allow GPS or other devices are simply lazy and don't care about their customers. I don't buy their tickets.