Think this through. Like, really, think this through.
What’s the goal? You want to steel a car? Rob the passengers? Kidnap the passengers? Kill the passengers?
So what are your options in this world where there is the equivalent of a firefighters key in elevator, but probably using PKE and periodic private key cycling?
Steal a key? From where? Buy one? From who and for how much? Ok, so now you’re needing to commit some rather risky crimes before you even move onto the next step.
And then let’s say you get the key. So you disable a taxi. And then what? I assume the passengers can lock the doors. So you smash the window open and, well, maybe it’s best to have a gun…
But why not just get a gun and approach someone stuck at a red light?
Why kind of risk/reward calculus is going on inside the mind of the criminal deciding to forcibly stop a moving vehicle and rob or murder the passengers?
So yes, what you said is true, but the likelihood is very low and the benefit to emergency responders is high.
I guess it makes for a good plot device for a spy movie.