Has anyone run/tested an agent payment setup with just a small funded balance and no other limits?

Was catching up recently on the latest developments on agentic payments and noticed a bit of a trend.

Cloudflare's wallets have an account wallet that funds a virtual wallet the agent spends from, with an allowance, an allowed seller list and a max transaction size. AWS's agentcore does payment sessions, scoped and time bounded, with a spend limit inside. Circle needs a human key share before anything moves. Coinbase does session caps plus per transaction caps.

The common denominator or practice seems to be the agent getting a sub account with a small(er) ballance instead of getting access to the main wallet, which means anything after that is a second brake on top of it, and that's where all of the above mentioned picked a different path.

Is this second brake doing any real work or is it there mostly there so nobody has to be the project that shipped an agent with no limits. If the sub account only has 20 dollars in it, then worst case is 20 dollars.

Has anyone been curious/brave enough to run an agent with some petty cash and no second brake on top? Would be interesting to see what path the agent would go on.