ISPs in the US initially used unmetered access to compete against legacy services like Compuserv that charged per-minute. It also helped that they didn't typic

ISPs in the US initially used unmetered access to compete against legacy services like Compuserv that charged per-minute. It also helped that they didn't typically incur per-minute charges on their phone lines, and after 1997 or so, could buy heavily subsidized lines from startup competitive telephone companies (who in turn typically WERE collecting a per-minute charge when the end users called into those lines from the legacy local telephone company.) Once an ISP got big enough they could connect to the SS7 network and buy inter machine trunks. Those did have per-minute costs, and very high startup costs, but they were so cheap compared to even the subsidized T1/PRI prices it didn't really matter.