More specifically, a North American thing. They also exist in some other markets, but generally not in Europe, as you noticed.

I have no idea if they are required by some obscure law, or if it is just tradition. Probably the latter. I don't know anyone who has ever used the panic button in a panic, but almost everyone can remember hitting it by accident.

Depends on the range, but if you're inconsiderate and can't remember where you parked...

You can hold the fob under your chin to increase its range, using your skull as a reflector.

It sounds crazy, but it works.

Can confirm.

I had one here in The Netherlands on my Volvo. I also remember setting it off accidentally many times.

I second this. What's a panic button?

A button on the keyring next to lock/unlock doors to start an alarm, generally honking and flashing the lights. Nearly ubiquitous on cars in the US, though personally I've never seen one activated for anything but a mistake.

I mean. You may never see someone use the panic button legitimately. The idea is that if someone is following you to your car, or threatening you you can hit that to garner attention and hopefully scare somebody off. That’s never happened to most people I know. Doesn’t mean it can’t be a useful tool if used properly.

Mistakes happen so often I question if it garners attention anymore.