It is possibly your own reputation with the factions offering the missions.
A couple of days ago, I was getting better missions than that, in a relatively strange place. I jump less than 100ly for my missions and can get between 2 and 5 million per trip. That said; sometimes, I just have bad days, where there is nothing worth while about. Lots of multi-million credit, sightseeing missions over 20Klys, but little else. Even at my home base.I don't think so. I am rated allied with all factions in the system. For example, the average 1 to 3 million credit mission has a travel distance of around 1000 LY. I can easily do cargo missions for that amount to systems within 15 LY.