I'd buy the technically impossible angle.
Even if you manage to get your microservices to synch every penny spent to your payment account at realtime (impossible) you still have to waiver the excess, losing some money every time someone goes past their quota.
I invite you to look at the various solutions implemented by those public cloud providers that actually implemented this feature.
"I can only do the job pretty damn well, not perfectly, so might as well not try."
I'm with you. And what do you even do when the quota is breached, nuke the resources? People will complain about that just as much as overspends.
I don't buy the 'evil corp screwing people' angle either. They are making farrr too much legit money to care about occasionally screwing people out of 20k and 50k.
Sure, but 80 -> 28,000 -> 54,000 is a hell of a lot of slippage.
Trading platforms can guarantee a maximum slippage on stops, and often even offer guaranteed stops (with an attached premium), so I don’t see why Google and Firebase can’t do similar.
The way it works at present is ridiculous.