Is it not possible to just make satellite behave like comets so they burn up in the atmosphere? Say that you add a rocket thruster that thrust the satellite in a downwards path so it burns up?
Only larger satellites have active propulsion that would be capable of doing this.
Propulsion systems are heavy, and would add significant cost to satellites.
Incidentally, if you want to get out of orbit, you don't thrust 'down', you thrust 'backwards'.
All of these problems can be solved with money. If a growing problem can be solved with money, it just hasn't grown enough yet.
If you could figure out a way to collect it then you've got resources that have already been accelerated to orbit...