That would make sense to me. I wouldn't even be surprised if some registrants are unable to pay in USD or if they get charged exorbitant fees for foreign exchange.
Even if the registrars added a warning during checkout with a link to an explanation of how it works, I bet very few people would read it. They'd probably have the same number of upset customers and the complaint would shift to registrars hiding a complex pricing scheme in the fine print.
My hunch is the OP is an extreme outlier and the issue happens so infrequently that the complexity of explaining it up front isn't worth it. In the past ~5 years this is the first time I've seen someone with a receipt and a legitimate complaint.
I think some of the responsibility can fall on the OP too. They say they've registered hundreds of domains, so it's not unreasonable to think they should be spending some time learning what rights they have as a registrant, how disputes are resolved, how long term pricing works, etc., especially if they're registering premium domains.