We have a bunch of different protections in place, every account has a billing account cap by default (see: https://ai.google.dev/gemini-api/docs/billing#tier-spend-cap...), in the addition to the ability to set more granular developer spend caps.

See also: Why is the default cap so low? I lost €78bojillion because my API stopped working.

Demand on-call phone numbers, autodial the entire company when it looks like they’re about to lose their first bojillion.

No, you don't really have to give Google a bunch of phone numbers. The input box will also accept entry of the following text:

“I'm a big stupid idiot, and when my API stops working, which it will, it will be all my fault and not Google's.”

Monitoring could pick this up in minutes rather than how long this took to discover

Monitoring could have detected overspend as well.

My point is either choice, caps or no caps, has its cons.