Requirements aren't crazy. It just needs to support uncompressed 96/24, full duplex.
Must work at 2.4Ghz--even in the face of 200 WiFi access points and 3 times that number of devices.
Must stay in sync to within a millisecond ... even though there is a large bag of RF absorbing water in between them.
Should work on a battery smaller than a thumbnail.
Should process audio but not generate enough heat that you notice it in your ear.
I can go on. The engineering requirements are quite severe.
... for something that we can do with a 10 cent wire, ironically.
At low range and less than 1/100 the speed of wifi.
> Must stay in sync to within a millisecond
If you have a working data connection at all, that level of sync is trivial. It only takes a few bits to align things, and they use pretty big buffers.
> even though there is a large bag of RF absorbing water in between them
That's hard.
> Should work on a battery smaller than a thumbnail.
That part is quite hard. But also it doesn't apply to over-ear headphones.
> Should process audio but not generate enough heat that you notice it in your ear.
I'm skeptical of that part being hard. How many milliwatts do those codecs take? Also once you add the battery constraints then the heat levels solve themselves.
Previously there hasn't really been much official support and implementations are messy and differ across platforms.
Source: have worked with various BLE stacks. Getting this stuff working well is difficult. I have much respect for companies that actually get it to work reliably.
Funnily enough, I try to avoid Bluetooth as much as possible and everything is wired on my setups.
- The AirPods Pro and AirPods Max generally work well. I've experienced most of the annoyances the OP lists occasionally, but not regularly, although the "autoselect the device want you want" outsmarts itself semi-regularly. (Not quite enough to make me disable it, but it's close.) I have never attempted to control the volume of the AirPods Pro using Siri because it sounds like a bag of hurt.
- My Bose SoundLink II will immediately say it's connected to the last device that it paired with when I turn it on, but sound won't come out of it. Depending on what seems to be random chance, either it'll start playing in ~15 seconds, or it will repeat its "Connected to [Device]" voice cue and then immediately be available for play, or once in a while it will put itself back in "I'm not connected!" mode and I will have to go into Bluetooth settings to manually connect.
- My Vanatoo desktop speakers have Bluetooth, and once they're connected to the phone they don't want to let go. I'll have successfully sent sound to the SoundLink, or the AirPods, or just the phone's own speaker, and then suddenly the sound will mysteriously vanish because the Vanatoos have woken up and grabbed the signal. (This sometimes happens before the Vanatoos have powered up their own internal amplifiers.)
- The Bluetooth pairing in my mother's car consistently has the weirdest behavior: I connect, it starts playing a podcast or music, and the audio just cuts out every four seconds or so at a regular cadence. It seems like it might be playing just a little too fast and there's a buffering issue. If I disconnect the Bluetooth and reconnect it, then everything's fine. But the first connection after the car starts will always be broken.
I mean, I know that's all anecdotal. But at least for me, the AirPods are the least broken Bluetooth audio devices I use. I get that "it works less frustratingly for many people most of the time" is not nearly as catchy as "it just works," but until Bluetooth gets properly sorted out in 2083 or whenever, I guess I'll live with it.