Note that the actual law[1] doesn't say how impaired driving is to be automatically detected. It could be something like requiring the driver to wiggle the steering wheel in a certain order before the car will go anywhere. Or it could passively monitor the driver for sudden braking or swerving out of the lane.

We'll have to see how the regulators interpret it.

[1] - https://www.congress.gov/117/plaws/publ58/PLAW-117publ58.pdf