[gregoriol]

Satellites have propulsion and sometimes adjust orbit.

Maybe a bolt wont break your car, but a nail will flatten your tire.

And most of the time we don't clean much the highways: a lot of small debris end up here and there...

The problem is indeed that cleanup is expansive and not interesting when it's not such a big hazard, but after some time the sum of those small hazards become a big problem, and the sum of cleanups almost impossible.