It's not even that entirely. The issue is the still shite systems manufacturers install and their proprietary nature.
I'm sure outfits like Sonic Electronix and Crutchfield won't be in the car audio business in 20 years.
The basic systems may be crap, but many premium audio brands have been involved in creating higher-end audio/entertainment systems and some names might surprise you. Infinity during their good years, Mark Levinson, JBL, Polk during some of their best years and later, Focal, Dynaudio, B&W and others were involved- the car brand usually depended on country of origin.
As long as someone makes products that can be bought for less, they'll be troweling it out in bulk. Also, cars don't stop working at a specific time, so old cars that are popular will be upgraded. I asked the guy at the shop if he needed some brand-specific tools and he didn't even know what they were because the older cars his shop works on are all GM and those tools weren't made for them.
I would like to see a new installer react to seeing an OEM radio like this-
