> Or how about when the criminals discover that they can avoid being shot by dressing up in police uniforms, fooling all of the smart guns?

Dressing up in police uniforms is illegal in some jurisdictions (like Germany).

And you might say 'Oh, but criminals won't be deterred by legality or lack thereof.' Remember: the point is to make crime more expensive, so this would be yet another element on which you could get someone behind bars. Either as a separate offense, if you can't make anything else stick or as aggravating circumstances.

> A very similar story is the idea of a drink driving detector in every vehicle. It sounds good when you imagine it being perfect. It doesn’t sound so good when you realize that even a 99.99% false positive avoidance means your own car is almost guaranteed lock you out of driving it some day by mistake during its lifetime, potentially when you need to drive it for work, an appointment, or even an emergency due to a false positive.

So? Might still be a good trade-off overall, especially if that car is cheaper to own than one without the restriction.

Cars fail sometimes, so your life can't depend on 100% uptime of your car anyway.