1 - they burn in atmosphere

2 - each satellite is under observation by a team

3 - how many satellites do you think are there actually? Not that many, unlike the driverless cars we are setting up nowadays

4 - Earth is actually big. Satellite pouring down all at once and you'll have maximum like 100 casualties - worse case scenario if 1). doesn't happen. Cars OTOH are in busy cities. One battery to explode and can easily do 100 casualties