If there's a distinction there I sure as hell don't see it. Either you satisfy the conditions (testing, prod) or you don't. Don't test in prod. If that seems questionable for any reason that's a clear indication your dev and/or testing environments are lacking and you know it.
You’ve legitimately never tested something you built in production, after having already tested it in staging and local? You’ve just, had complete faith in staging production environment parity your entire career on every project and it has never failed you?
Oh I did all kinds of dumb shit over the course of a 20 year career, make no mistake, and testing in prod is the least of my sins. That doesn't make it any less stupid, and in the case of testing payment gateways pointless. If you're in test mode you're going to rub up against the same endpoint you would in live. Either the card info you package and send validates or it doesn't. Using a test card doesn't alter your level of control over the situation in any way, it all goes down on your payment processor's servers. All testing card processing with a live card in prod is going to buy you is bullshit transaction data in your live datastore, and maybe a little less anxiety if it's your first time. OP is having a panic attack over card processor TOS though, so they're jammed either way.
You don't believe that people write payment software? You don't believe that people deploy payment software? This is a firm requirement. You risk losing your PCI certification, your payment processor certification, or if a customer your payment processor account.
“Penny testing” is common in the real world, and isn’t limited to verifying bank accounts. It’s more broadly used to describe testing with very small amounts in production. That’s my experience anyway, working with various payments processors and BaaSes.
All I know is when I was writing systems used by franchises/gas stations there was zero tolerance. Maybe BassSes are so bad at moving things to production they had to loosen that up.
Yeah same, I've built a few integrations with payment gateways. I make extensive use of the test environment, for sure. But when it's gone live I've always done a single test purchase with a real card, just to be sure, and checked that the transaction appeared in the appropriate dashboards and reports from the payment processor.