Intoxicated people aren't sneaking away to drive home, they leave less intoxicated folks and get in their cars every single day. The potential to be an accomplice, especially one that is very unlikely to be charged, is not a great (maybe not even good) deterrent. You'll have to live with it, and that will be awful, but people aren't thinking about all those potentially terrible outcomes when they let an intoxicated person get in the car or get behind the wheel themselves. If they were, and it made them not drive, or stop their friends from driving, or suggest a stranger get an Uber instead we wouldn't be having this discussion at all.
I'm also not sure how the camera would detect that you were drunk prior to starting the car... maybe require something akin to a field sobriety test? Add LED's to the camera housing that "instruct" you to look left-right-left (randomized), while also checking pupils? With determination and know how I would also imagine it could be tricked (you could just be lucky and guess the randomized left-right-left) but that isn't a reason not to put a safeguard in place.
A combination of breathalyzer (even with its problems) with the ability to prevent the car from starting that also requires random tests while driving, along with a camera for real time monitoring (for general signs that a person shouldn't be driving, not limited to intoxication) is likely the most "foolproof" method. Both the random breath tests and the camera monitoring would benefit from the ability to enable the hazards, tap the brakes/shake the wheel, pull over safely and/or slowly bring the car to a stop if needed. With semi-autonomous cars this is realistic, but not so much with older cars.