CarPlay (and Android Auto) are basically driving-oriented UIs that your phone pushes to the head unit in your car. This means you get a full touch screen UI with your maps and music apps of choice, plus other apps that support it.

It beats mounting your phone over an AC vent because the screen is bigger and the UI is actually designed to be safe to use while driving (fewer, bigger buttons, more use of screen edges and corners so critical functions can be activated without looking).

Car makers don't like this, because it means users are less likely to pay subscription fees for their shittier built-in internet services.

You can use all the apps you are familiar with and have already set up. Like you favourite maps software, your music subscription like Apple Music or Spotify, or things like podcast or audiobook apps, everything right on the big screen of the car.

Main reason is that many apps have a separate CarPlay or Android Auto UI that is less distracting, more glanceable, etc.

It’s kind of hard to go back once you’ve lived with it for a a bit. It’s much more convenient. A simple phone mount feels kind of janky and distracting afterwords.

Yes. I don’t like to look at or touch my phone while I’m driving. Its dangerous. CarPlay makes it safer and easier to control my phone - from which I play my music and do my navigation. My current car has Bluetooth, so the music works, but I still have to use my phone to control it. Which as I said, I don’t like to do.

If you're talking about a head unit replacement that get's difficuld nowadays since they aren't just Double-DIN and there are vehicle.settings managed in there.

Looks like to do that for mine is about $800-1500 DIY