Saying it's not fair to compare them is like saying it's not fair to compare a minivan to an SUV when making a car purchase. They're different, but similar enough.
Bluetooth is so old that it was coming into use when Computer Shopper was still published. It's been a dumpster fire of compatibility since its inception.
There's one of two culprits on the Android side: either its the device drivers, or the OS itself. Device drivers should be capable of being subjected to stringent acceptance standards in order to advertise "Bluetooth". If it's the OS, that's even worse since it is higher up the abstraction stack. At least the device drivers being closer to hardware have an excuse.
Bluetooth is 26 years old. A 26 year old industry standard should be better than a coinflip as to whether some bluetooth thingamajig will work with a mobile OS. It's just sad.
My theory was iPhone probably got tested on most 3rd party accessories. However, the fragmentation in the Android space meant I’d have no idea what devices they actually tested with.
This is further compounded by the fact that Android isn’t really an open platform, at least in a practical sense. I can’t just load up a patch for something (assuming it exists) without fully switching to some open source ROM that’s going to come with its own issues.