Cost of Fortifications and Infrastructure

With Industries lvl1 increases production 35%, lvl 2 65%, and lvl 3 100%.

With Recruiting Stations lvl 1 increase manpower 35%, lvl 2 65% and lvl 3 100%

So in these two, yes level 2 should be more pricey then level 1, and 3 more then 2.

But now looking at Fortifications and Infrastructure.

Fortifications decrease damage taken 15% for each level

Infrastructure increases speed by 66% for each level.

So rather then a rising cost for each level, shouldn't all levels be the same price? Maybe the present level 2 price should be applied to all 3 levels.

............

Just looking at other buildings, Propaganda would be part of the first group of rising rewards, but local ports and airstrips would be in the second group.

So to have all airstrip lvl 1 now cost the lvl 2 price would be hard on me. So maybe just go with the level 1 costs for upgrades. Might get more people building roads and fortifications. And why have an airstip level 2 cost more then a lvl 1. What's wrong with a level 2 being just twice the cost of a level 1, instead of twice plus.