No one is saying all programmers lack engineering discipline. It is simply not required for all programmers, even in many situations when it probably should be.
Why not have sub agents talk to a payment service? Sub agents should ultimately be associated with a human or business entity, the human or business entity could provide a single payment service for agents.
Maybe it’s just my lack of imagination, but I don’t see a use case for giving agents money when they can barely be trusted to not break out of a sandbox and cause hallucinatory chaos.
Let’s say for a minute this is a failure of my imagination. Does each sub agent really need to be able to independently transact?