When you buy a TV would you consider those that have RCA and component inputs but no HDMI?
		
		
	 
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I don't think this analogy is apt.  
For devices that input to a TV, HDMI is the de facto connection these days.  I would say almost 100% of dvd players etc send HDMI signal out.  
To the contrary, the inputs to a car stereo are not 100% apple phone...  They are disparate.  Some exist on the stereo itself (xmradio, am fm), one is a long standing wireless (BT), one is an extremely long standing analog (aux), but phone/app-specific connections are recent.
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So (specific-phone) -play / -auto are technologically new to the scene, and car makers are trading off the expense (and errors associated with integration) of private device standards/implementations that may or may not even exist in future years, in a backwards compatible format, with the probable benefit (satisfaction of customer base that just happens to have a certain phone now).  
That ties the risk management of one company (car maker) to another companies potential poor implementation of their entertainment/communication device.  And, weirdly enough, from one category of devices (automobiles) to an entirely different category (communications handsets).
Unfortunately for car makers, that is their new reality.
I just wonder if all the effort spend going into infotainment could otherwise correct some gross (almost negligent) standard automotive control implementations that actually hamper the driving process, like interior lights that cannot dim or turn off even when it makes night driving worse, cruise control that disrupts certain freeway passing maneuvers, distracting warning notices that cannot be cleared to see actual driving info, and more.
Drive safe out there!