The problem is fraud + disputes. Who's liable for people sending money to fraudsters? For letting fraudsters operate on the platform? See the fraud issues of Zelle, which is basically a free money moving service comparable to FedNow.
The service the networks provide is a way for all participants (banks, people, businesses, etc) to trust one another, as well as a healthy rules-based system to address disputes. Getting this working is not trivial.
The service the networks provide is a way for all participants (banks, people, businesses, etc) to trust one another, as well as a healthy rules-based system to address disputes. Getting this working is not trivial.