The "brains" of the system, namely the phone, can be easily upgraded as technology changes. People will get new phones. Operating systems will be upgraded. Apps will come and go. Maps will update. The system will keep working flawlessly.
This can't happen with fixed hardware in vehicle - the firmware and apps will be promptly outdated.
iPhones are always faster than the infotainment systems in cars due to development cycles and cost.
Now my iPhone is eight years newer than the one that was already better than my car. So it’s obviously faster. Apple has delivered numerous new features in those eight years, the car never received a single update. That wasn’t even an ability on the car.
As John Gruber is a fan of saying, the phone eats everything. You can’t compete with it. It has better specs, it gets updated more often, it’s more customized to the user. It has better connectivity (I’m not paying $30 a month or whatever to give my car cellular service).
It has the apps I want to use, not the ones who gave the car company a payoff. If I have to get a rental car on a vacation, all my same stuff is right there.
GM will suffer. I’m curious how long it takes them to reverse this. Just one year? Or more? I’m willing to bet a nontrivial number of people just flat walk out of dealerships when they hear the car they’re looking at doesn’t have CarPlay (or Android Auto).
But the software on the screens is great! Not something that can be said about, for instance, Ford SYNC (TM).
There's a whole weird gray market for Chinese-manufactured "computers on a stick" that reverse-engineered the CarPlay protocol and use it to display a custom computer/Android interface in your car. You can do things like stream Netflix, use Chrome, install any Android app, play games, etc.
I'm not recommending it as it seems both sketchy and unsafe, but it's a funny niche that exists. For some reason, they are usually marketed on AliExpress as a "Car AI Box" but of course have nothing to do with AI.
Here's a random example video of what they look like: https://www.youtube.com/watch?v=LrFHjrYnoDE
Nothing about “Operating systems will be upgraded. Apps will come and go. Maps will update.” says “The system will keep working flawlessly.” - if anything, the system will accumulate flaws.