> Saving (what I would I guess is) at most a few dollars per uniform

It really doesn't make a material difference to your point, but just to note that it isn't just a few dollars per uniform. A soldier's webbing, bergen and day sacks (all their battle load carrying equipment) is highly personalised, takes a lot of time to break-in, and takes up a lot of space. Maintaining three or four sets of that in different patterns for different environments would be a huge hassle.

A single pattern effective almost everywhere makes more sense than in just simple money.