Infotainment controls many of car systems. For example, infotainment controls car drive mode, which instantly affects gearbox. Probably requires predictable time delays for certification.

fast boot, low latency for buttons/controls.

I have a Ford Sync 2.5 system which is a cost reduced hardware downgrade from QNX based Sync 3. I'm sure the OS is doing its best while hobbled by a poor management decision but it has lots of bugs that crop up from what appears to be severe RAM shortage coupled with some gradual memory leaks. I have to reboot it regularly when traveling with Android auto. It's always a crap shoot if my phone will connect.

No gpl, and more importantly the gpl 'fans' who can't write a line of code but will scream about gpl violations if they can find anything - even if false.

it run qt and does everything else so it is often an easy choice.

In some cases it could also be an Android guest running as a VM on the QNX Hypervisor, where there are multiple guests (QNX, Android, Linux) making use of the same HW.