Use cases: where network effects in America built the railsCard acceptance is the founding case study. The Precedence Research digital payment analysis shows point-of-sale transactions still carrying 53 percent of digital payment volume, evidence that the physical economy joined the network rather than fleeing it. Data networks built the third rail quietly. FedNow and RTP are racing through the adoption curve that cards walked over decades, compressed into years because every participant already understands what joining a payment network buys. That convenience is network density wearing everyday clothes, and it is easy to forget how recent it is: universal person-to-person transfer arrived within the past decade.