PayPal's shift to merchant checkout (2000s)
PayPal began as a person-to-person payment tool on eBay and added a merchant checkout button that let buyers pay from their account balance or linked cards without sharing card details.
The checkout button became a trusted alternative to card entry, and PayPal grew into one of the most widely accepted online payment methods.
It showed that a peer-to-peer payment network can become a mainstream merchant payment rail once enough consumers hold balances in it.
Cash App Pay is the modern version of that shift: turning a balance held in a peer-to-peer app into a merchant checkout method at scale.
