The problem is that judging whether the circumstances are appropriate is nearly impossible from the limited perspective of the driver. You can't see things hidden by A/B/C pillars, you can't see short objects (like children) obstructed by your doors, and too often people using cars forget that things like kids on bikes, motorcycles, pedestrians, etc. exist.

This is indeed normal human behaviour, but we've also seen a dramatic increase in drivers killing people with their cars.