FedNow is still roughly an order of magnitude more expensive than the EU's TIPS (EUR 0.002 vs. USD 0.045, last time I checked) in terms of "sticker price", but yes, at least there's some movement, and as you say I'm not sure who actually pays that sticker price in the US.

The real problem is that, even if costs were to come down to zero, there is nothing incentivizing banks to actually make RTP available to their customers. In the EU, customer-initiated "push" bank transfers are considered an essential part of a checking account; in the US, they're not.