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GM blocks dealership from installing Apple CarPlay retrofit kits in EVs
(www.theverge.com)
This is a most excellent place for technology news and articles.
It was a lot more practical for new players to enter most of these markets back in the 90s, before the megacorps started to fully metastasize. Deregulation [of some industries] wasn't the objectively bad choice that hind sight makes it seem like back then, just something worth trying to see if it improved outcomes. Remember, regulations are supposed to regularly change to meet the needs of the time, not be a lifetime commitment one way or the other that the political deadlock of the '00s and '10s made it seem.
Almost the entirety of US car manufacturing is done by three carmakers. It's been like that since at least the end of WW2.