[wartijn_]

About your last paragraph: the goal of these measurements would of course be to prefect you from driving at all when alcohol is detected. Suggesting that the idea is that people are slowed down on a freeway because of this seems absurd.

[Brian_K_White]

failing to project that this would happen all day every day everywhere, is absurd

[wartijn_]

No it's not. Car manufacturers and regulators have been trying to make cars safer for decades and won't just (require to) add some feature that is as unsafe as your proposed "solution" And the solution here is simple: do the check when the car is starting and don't drive when alcohol is detected. That's how current alcohol locks work. Nobody is suggesting to test when the car is already driving and nobody is suggesting to slow cars down.