I stayed in a hotel room recently that had a nice Sony music system, with a USB port. I had my iPhone with me with a lot of music on it, and a USB cable, so I plugged it in, hoping to enjoy great music when on vacation. But it didn’t work, presumably because the music system was expecting a USB Mass Storage protocol and not Apple’s proprietary protocol.
This reminds me of an earlier time when I tried to plug my Nexus into a hotel room music system, and it didn’t work either, this time because the Nexus uses a different protocol, called MTP.
So, the industry has come up with three different protocols to plug phones in to music systems: USB mass storage, MTP, and Apple’s proprietary protocol.
This is not even getting into physical ports, like type C, micro USB, Lightning and 30-pin. These are also a nuisance, but can be worked around with the right cable, which most people have for their phone. But if you do manage to physically plug it in and it doesn’t work because both sides decided to speak different protocols, you can’t do anything.
I spent my vacation without listening to music.