Or put an automatic 24 hour hold on any new recipients. You can enter the transaction, the recipient gets the notification but with the qualification that it's pending.

That would pretty much put a stop to the robbery problem without being an issue for the legitimate user as it's only intended for friendly situations anyway.

Now the robbery turns into a murder?

They probably would just need to kidnap you for 24 hours, but murder would also work. Depends how patient they are and if they have the manpower to guard you for 24 hours.

Anyone who goes around murdering every robbery victim is going to have an awful lot of police hunting them. It's not a viable path.

Zelle at major banks already does that. I can't transfer more than $2k-$5k into my own account of many years at a different bank, and I'm pretty sure the limit was more like $500 initially. Honestly, I have no idea how to steal $50k from anyone's banking app. Maybe a wire? Haven't tried via app. Not to mentioned whoever you're wiring to has been KYC'd. But certainly not through Zelle at US top 5 banks.