I find the car signalling problem interesting.
Where I was born people trust the turn signalling and drive early. When I moved to the UK I (luckily) quickly realised you cannot do this here. Everyone waits until the car actually starts turning before driving. Even if it's signalling, no one trusts that, possibly creating less pressure for correct signalling. It makes traffic slightly slower but avoids the possibility of (this type of) accidents.
Counter-intuitively, worse drivers leads to fewer accidents.