This is what I thought. There's evidence of this throughout the game already. Just because a system doesn't have any stations, doesn't mean it has no industry
It's great the planets already have cities and infrastructure ready to go. We are just waiting for the expansion to allow us to travel to them. 500ms is too slow, super cruise is mass locked. So perhaps a drive capable of ultra sonic speeds - faster than sound but slower than super cruise - where you can't engage in combat but can still be interdicted will work well for planetary entry and inter-continental travel.
The ultra-sonic drive would engage where the current target exists on any planetary body but you're too close for super-cruise.
At 500ms it would take just over 3 hours to travel from London to New York. That's way too long. So I'd say the max speed of the ultra-drive should be around 20kms (the journey would take less than 5 minutes, ignoring acceleration time).