The most obvious one is PayPal. That may have made sense in the '90s, but today I should just pay money to eBay, they take their cut and send the rest to the seller. Instead I pay directly to the sellers PayPal account, which may be named something completely different from their eBay account. Then eBay sends the seller an invoice at the end of the month or something. All unnecessary complexity, but I'm sure someone would be outraged if they changed anything.