I recently went on a trip with several friends and we rented a new Ford Expedition. The integrated audio system in the car supported multiple Bluetooth devices with a history (including previous renters) but as far as I could tell not more than once device at a time. Every time we started the car we had to select Sources -> Bluetooth -> Connect -> ${device name} -> Sources -> Bluetooth -> ${device name}. It was a huge hassle and a 3.5mm cable would have been far easier and sounded better.
So one interesting aspect of the airpods is seemingly automatic pairing, without having to dive in settings, through what seems like near-field communication. I'm curious to see if they've solved the multi-device pairing problem too.
The thing is, the pairing UI is rarely the problem. It's the actual pairing implementation. Pairing a phone to a car is usually just a few button presses. Not quite as convenient as NFC or whatever, but not a real problem. The problem arises when you find that Pair button and press it and then it doesn't work and provides no feedback on why it failed. Cue five minutes of screwing around turning things off and on again and finally giving up.
