[saarons]

"because they can" is probably the best answer. Before RTP, which is still rolling out, wire tranfers were the only way to do same-day, non-reversible, high-value payments. On occasion we also see that wire transfers being sent manually need what's called "repair", as in the sending party didn't put enough information in the wire so the sending bank or receiving bank have to go get a human being to figure out what went wrong. Repairs and rejects add to the operational complexity of wire transfers and probably contribute to the higher end-user cost of sending one.