Someone here mentioned navigation obstacles. There is an interesting gem, whilst the SPA, Scout service, Naval Auxilleries do everything they can to keep the flight paths clear in the approach to the Main World. When things get further out or in a different milieu (IW, 0,or TNE spring immediately to mind), then things could get much hairier. Whilst, they are not likely to jump into a comet (as that would be a catastrophic misjump) they could be directly in front of potentially more dangerious in the tail.
Spaceports would have limited capacity to broadcast this information throughout a system relying on good old fashioned radar dishes. That combined with a lack of coordination based on hinderance such as TL, relations with the SPA, a growing independence movement, etc.