Some platforms work like this (Amazon) and some have fees you have to pay after the fact (eBay). Big reason why eBay works like this is it has listing fees for high volume sellers and they have to be paid even if the item doesn't sell. Also, in the early days payment wasn't handled by eBay itself, it was decided entirely between buyer and seller. eBay auto is still like this (as far as I know).
But even with Amazon you have to have a credit card on file and they'll charge it if your seller account goes negative. Your seller account can go negative if you have a return or if you paid for FBA shipping and haven't made sale since or paid for FBA removal.
But even with Amazon you have to have a credit card on file and they'll charge it if your seller account goes negative. Your seller account can go negative if you have a return or if you paid for FBA shipping and haven't made sale since or paid for FBA removal.