Simple: everyone is looking for the next big platform. The smartphone revolution came by surprise to most and it has taken years for companies to catch up. Everyone is racing because they don't want to be caught with their pants down again.
It goes way beyond hardware. Whoever controls the car as a platform in theory controls the services layer that would be built on top of it (ride sharing, delivery etc.) and also the captive attention of the cars' occupants outside their phone. Then there is the data that comes from a device that takes you wherever you want to go, with tons of internal and external sensors to get data on occupants (unique identification will be trivial for audio ads, etc) and their external environment.
My guess is Google sees the rather low margins of cars and would much rather focus on what is likely substantially higher margins (and far less capital outlay) on the software side which is much more closely aligned their core strength.
Catching up isn't easy, you won't be able to just reverse engineer it.
> Catching up isn't easy, you won't be able to just reverse engineer it.
No, but the California-based employees with an understanding of that system will be able to get a nice payday when they start working for a competitor.
Is there still a no politics policy on HN?
-- POLITICS BELOW-- Also it'd be interesting to see in the Age of Trump if Google would be red-taped if tries to sell the tech overseas, Trump would probably solicit bribes from the Detroit people to put up such a law.