> Just like in real life, if you run out of money you have to stop doing things

In real life when you hit your card's limit, your transactions get declined. Straight away.

I had this last month in a supermarket after my (personal) checking account didn't have enough money to cover my purchase, I'd completely forgotten to transfer money from my business account.

My bank wasn't prepared to let my account go overdrawn, not even by the equivalent of $20, which is absolutely their right.

Amazon, OTOH, benefits in lots of ways by not implementing this mechanism.

A better analog to the store and Scamazon's implementation would be:

You put stuff in your cart.

You go through the register. You agree to "prevailing price".

No prices show up because they are "calculating".

You leave the store.

A day later, you're hit with a surprise bill that's 10-100x more than you though. A $100 transaction ends up being $1000-$10000.

There's no refunds.

The dispute procedure is to beg and hope they "let you ignore it".

> In real life when you hit your card's limit, your transactions get declined. Straight away.

Except for when it doesn't. I've got two primary current accounts, one with a "legacy" bank in the UK and one with a modern bank. The legacy bank is happy to let me go into an unplanned overdraft, and charge me for the privilege of doing so.

> a "legacy" bank

"Been there, done that". Not there any more!