I recently built a 3-star terminal with jetways and have assigned capacity to my airline. It appears as if it is being used as I can now see an "available capacity" which is less than the total capacity. However, if I look at my flight ratings I am still only receiving a 1 bar rating for terminals (the same as using the default AS terminal). I am sure this cannot be correct as then there would be no incentive to build one's own terminals.
Please could you assist, maybe I am doing something wrong?
Well, the rating is correct, because the default AS terminal is also 3 stars with jetways (at airports where jetways are provided in real life), so you, effectively built the same terminal as AS Default.
If you want better ratings, you will need to demolish your 3 star terminal and build a 5 star terminal with jetways.
That seems like a rather redundant feature don't you think? Why have the option to build terminals that have the same as or worse ratings than the AS default terminals?