I've worked at companies that were spending 6 figures a month on AWS and we had dedicated AWS employees who helped us understand our bill and keep pricing in check. We also had GCP and Azure reps constantly reaching out to see if they could win us over by showing us how they could lower our bill. Overcharging enterprise customers for things they're not using is actually a risk to AWS as it gives customers a reason to jump ship.

The whales on AWS aren't overspending because AWS uses the granularity of their billing to make sure they aren't. That's how they keep the whales happy.

For the little guys, I'm not even sure it's worth AWS's time to nickel and dime them. AWS hands out thousands to ten of thousands of dollars in credits like candy. I'm pretty sure it's more important to them to lock in whales when they're still minnows than to bilk an extra $500 a year out of a 10 person start up.