I haven’t seen any studies on who is purchasing the air or how much data they use so that’s a big assumption to say air users use less data than pro users but for sake of argument let’s says that’s correct. AT&T only sells unlimited data plans so they are going to make more money off someone that pays for unlimited data but uses less data. So an air customer would in turn be more valuable than a pro customer because they are paying the same price and creating less network congestion.
Even with "unlimited" there are limits after a certain GB threshold. Otherwise, AT&T would only sell one single "unlimited" plan. Air customers would be more likely to choose the low-end "unlimited" plan from AT&T.
We see the same strategy from Internet providers. Look at why Verizon is giving away a Samsung TV for home Internet subscribers and not a Uber Eats or Amazon gift card. They want you to consume more data.