Ideally a satellite is in a given orbit for years. If junk is destroying it in weeks or even months you’ve got a massive issue.

However a rocket is spending in a seconds in that same orbit. Thus a rocket passing through may only have say 1:10,000 odds of a collision on its way to mars while satellites are getting shredded.

integrate risk over time. if you have a high target orbit outside the "kessler belt" then you don't spend much time going through it. though this requires a fairly direct orbital insertion. slow orbit raising would have a higher risk, but even that would still be lower than for any satellite intended to operate for years and decades in an affected orbit.

It really depends on how much junk actually is there and in what orbits; especially at 500 km up, space is big. The surface area of the earth is 510.100.000 square kilometers, at 500 kilometers the 'surface area' is a multiple of that (I can't math), surely there's enough gaps or lower-density areas at that height even if there was a catastrophic Kessler Syndrome event.