Customer doesn’t give a fuck how long a billing system took to make, they only care that it works correctly.
A billing system only truly gets built once, then possibly maintained in perpetuity. This makes the advantage of building it 20x times faster pointless. AI builds it in a day, will it matter 5 years from now if that billing system was instead built by hand in 20 days a long time ago? No.
The speed advantage of AI only comes into play when you have a lot of code to crank out continuously.
Do you have a need to constantly build bespoke billing systems at a rate of 1 per day? Probably not. So who cares. Take your little AI grift charging $1000/month somewhere else. It’s not needed.
The customer cares how much it costs. And how much it costs is proportionate to how much time it takes to build. You’re conveniently ignoring market and price dynamics
Every billing system in use is constantly maintained with new features, bug fixes ane the like. The system of 20 years ago would apply the wrong tax laws today. the people asking for the new feature today care about how easy those are to add