I personally don't think they're hard to implement.

You need a module to create events that have the zap split tags.

You need a module to read events that have zap split tags.

You need a way to send a separate zap to each recipient according to the ratios.

And you need to update your UI for each new module.

But I can't for the life of me figure my way into the heads of nostr devs and why the prioritize what they do.