Thankfully, banks in general are in a stricter regulatory environment with a government-level watchdog you can escalate to, though that might not apply for electronic money institutions (or whatever the US equivalent is).

No, why do people think this? In the US banks have a right to refuse to do business with you for (almost) any reason and refuse they do. They are more likely to ban you than eBay. There's no right to have a bank account, there's no right to keep your back account - full stop.

This happened to me recently when American Express sided against me when Expedia essentially stole money from me for services it didn't deliver.

Now there's two companies I'll never do more business with.

Oh so far I've always found American Express to be much more reliable than all other banks when it comes to Chargebacks

Me to up until this incident. It's worth noting that AmEx has acquired some businesses from Expedia Group and Expedia Group itself is now a major shareholder in AmEx Global Business Travel.