Here's another problem. Colonization requires only 1 (one!) activity - cargo delivery. It may be fun for a week or a month. But development of a good colonized system (with current requirements) will take 1 year of full-time job. Placing 3-4 starports (at least 1 month for each), a few ground ports an settlements, a few space installations - in overall from 9 to 15 months. It's not fun to freight so long. No alternative activity provided, only being a space trucker.
Obviously, colonization should be more a strategy game, not a full-time whole year transportation. There must be different ways to achieve colony development. Strategy game is about making a concept and fund it. 1 year is already a long-term goal, there is no need to require from pilots to dedicate all their time during this year to only this single activity.
Alternatives may be like this:
a) pay money to NPC pilots for cargo delivery
b) ore mining, where rare materials (not sold at stations) may be an alternative to currently required materials (colonization ships may have a service to exchange ore to steel and so on)
c) convoy protection - protect cargo delivery for new colony from pirates
d) use of engeneer and odyssey materials - again, special service at colonization ship may exchange materials and loot from settlements to close needs with some materials required for colonization
e) exploration and exobiology data - may give a discount for colony construction
etc.