Bluetooth isn't the same as your WiFi network. Most of the comments here are talking about IP-based protocols that aren't relevant for Bluetooth anyway.
Bluetooth is probably the best example of a widely adopted protocol for connecting to devices and sending audio streams. The protocol isn't exactly the problem. It's the buggy implementations of Bluetooth stacks and Bluetooth software in embedded devices.
Getting it right is actually extremely difficult because Bluetooth grew in complexity to be everything to everyone. It isn't only an audio sending protocol. Almost nobody owns the entire Bluetooth stack, so it's a mix of pieces from different companies and vendors.
Apple's implementation isn't perfect, but from experience I can tell you it's 10X better than the nightmare that is Android Bluetooth. It's getting better, but for years you had to collect a lot of different Android phones so you could make your software work around all of the different quirks in each vendor's different Bluetooth stacks.