Re: ads to be viewed by 'locked in' customers
That kind of 'captive audience for adverts' game has been tried several times in the UK, maybe elsewhere, albeit not by Google, and not in vehicles. Post Office queing areas, doctors reception areas, even on buses, etc. Are any of them still operational and are any of them making money? Why would it be different in self-driving cars?
No, sorry, there's probably another reason behind it. Not quite sure what, it may well just be 'removing the cost of the low/no skill individuals in the driving seats', but captive audience for adverts probably isn't it.
At one stage a plan like the one you mention might have convinced some gullible investors that Google knew what they were doing and were worth a punt of a few billion, but surely Google are beyond that stage now?
Biting the hand that feeds IT
