Not sure what you define as larger account.
Counter real world example. I was doing some consult work for a place that had a 9k unexpected charge on AWS. They asked about it and I explained about how they could dispute it. They said ugh never-mind and just paid it. FYI it was a charity which I've since learned its common for charities to be wasteful like this with money since they are understaffed and OPM(Other peoples money)
So how is that a counter example? The client never asked for a credit. Since the startup I worked for, I have been working in AWS consulting - first directly at AWS (Professional Services) and now a third party consulting company.
While I have no love for AWS as an employer, I can tell you that everyone up and down the chain makes damn sure that customers don’t waste money on AWS. We were always incentivized to find the lowest cost option that met their needs. AWS definitely doesn’t want customers to have a bad experience or to get the reputation that it’s hard to get a refund when you make a mistake.
Of course AWS wanted more workloads on their system.
Semi related, AWS will gladly throw credits at customers to pay for the cost of migrations and for both inside and outside professional services firms to do proof of concepts.