The car manufacturers just contract it out to companies like Johnson Controls, who make the system in my Mazda. It's running embedded linux and the interface is a bunch of javascript files. One of the bigger problems I see with this system is that Johnson Controls just doesn't give a shit about maintaining an old system unless a safety issue is presented. They're better off selling improved systems for use in newer model cars as a sales tactic. Android Auto/Apple carplay pretty much remove the ALWAYSBEIMPROVING component. Johnson Controls could pretty much just sell the same head unit/LCD combo for the next 10 years and no one would notice.