The term “kill switch” is trying to get you to think that the police get a button to turn off the car, which is the one thing this law doesn’t do. It's a mandate for the government to devise a passive, local system within your car to detect erratic driving.

Here is a more detailed explanation of the bipartisan bill in question:

Specifically, Section 24220 of the bill directs the National Highway Traffic Safety Administration to develop rules that would require new cars to be equipped with technology that "passively monitors the performance of a driver," identifies whether they may be impaired and prevents or limits motor vehicle operation "if an impairment is detected."

The agency has three years to finalize the standards for which technologies cars should use, according to the bill. Automakers then have between two and three years to implement those standards. The earliest implementation date for the technology is 2026.

When laws were introduced to require seat belts in cars, with a legal mandate to use them while driving, people declared it an infringement of their rights.

https://www.businessinsider.com/when-americans-went-to-war-against-seat-belts-2020-5

When laws were introduced to toughen up drunk driving laws, people declared it communism.

https://www.youtube.com/watch?v=xSDniOoR3Lw

This is nothing new. Regulation should uphold public safety, and passive safety systems make sense in the age of information.

If I had to take a guess what the end result will be, it will probably just be a gyroscope that will disable the car if too much swerving/erratic behavior is detected. But because you can't just stop a car in the middle of the freeway, it will probably set an internal speed limit to the car just like a train does. Probably a speed low enough for you to get off the road but not high enough for you to hurt somebody even if you're drunk.

But all of that is nuance, and you don't often get that around here.