Remember that not that long ago viruses spread through floppy disks.
Today, people share USB sticks full of music from one car to another all the time. They also bring their music from their home car to a rental car and back.
It had the benefit of an information center with physical buttons too, so I could navigate around my library without touch screen madness or voice commands constantly failing to understand band and song names.
I've been doing it for years, since it's so much more convenient than the alternatives: plug the stick into my car and I have my whole music library there and it Just Works.
We use an USB key full of audio books: Harry Potter saga and The Quest of Ewilan among others. The whole family is hooked.
The car UI is much more reliable (no phone to unlock by the copilot, no Bluetooth disconnect). The phone battery is spared for navigation purposes.
Sure beats the radio, which plays 2 songs and then 5 min of commercials/sweepers, and has the gall to run ads on the HD text transmission on FM designed for song information.