I say it's up to your friend to construct an argument against the SDC engineering teams being aware of the problem or unable to solve it better than the solution we already have. I have a hard time constructing either.
Extraordinary claims require extraordinary proof.
If there is a manual override (wheel and pedals), the door is already locked when in motion, so the driver should have enough time to floor the gas and escape.
Unless Google incorporates some seriously advanced detection and response, I see SDCs being an easy target for criminals.
[0] http://www.latimes.com/business/autos/la-fi-google-car-20140...
How exactly would that happen and what fail-safes could google put into place to prevent those?
I don't know that they can prevent it through fail-safes. I think they can discourage it, at best, but as with any system, people will find a way to force the system to suit their needs.