Anti-lock brakes are regulated and must meet certain guidelines on functionality, safety, interface and so forth. They are provided as part of your car in a market that is rich with competitors. They do not prevent you from using your vehicle. They do not report you for driving "improperly", or force you to buy a new car. You do not have to pay a monthly subscription to keep them working.
Microsoft inspecting everything you do on your computer and beaming that information back to the mothership, complete with kill switch is a completely different scenario. Microsoft are functionally a monopoly. They behave like a monopolist and have proven repeatedly they cannot be trusted. They are not regulated by anyone. They answer to no one, excepting their massively corrupt and equally untrustworthy government.
Can you guarantee me that this kill switch won't be used on me if I do something perfectly legal in my jurisdiction but which the US has a problem with? How about if I am a political dissident? What if I am a journalist working with the next Snowden?
Can you guarantee that Microsoft won't use this kill switch on me if I use an authentication bypass on my operating system, or on any of my applications? In my country these aren't illegal, as long as I do posses a license. Bypassing the DRM in order to make it easier to virtualize/clone/backup/whatever is perfectly fine here.
What about if it accidentally picks up something as "malware", but isn't? What if I am journalist or grey hat hacker investigating a bot net?
Who gets to decide when Microsoft can kill my computer? How, exactly, are we assured that this won't be abused, by Microsoft or by a government? How do non-Americans have any say in how that regulatory and/or oversight process occurs? Once that capability is in place, what prevents any government - even not the US - from demanding and requiring access? You KNOW that China, the US, the UK and Australia will be in there instantly. Probably already are, as the EULA says MS has the right to do this, so the code is probably there, waiting to be used.
In short: Anti-lock brakes are a feature on a vehicle that is very specifically narrow in scope and in impact. They were and are rigorously tested and their use is regulated.
Oh, and my car DOES have a button on it that turns my anti-lock brakes and my traction control off (they are essentially one and the same system). The manufacturer put it in because they are aware that there are instances (such as when you are stuck in the snow and need out) that the ability to turn that feature off is very useful.
Another big difference is that when I push the button to turn the ABS/TC off, I believe it does, in fact, turn off. I don't believe for a second that turning off Windows 10 spyware actually turns it off (the damned thing still calls home) and I don't believe for a second that if they put in a "don't kill my PC" switch that they would honour it.
Microsoft cannot be trusted.