[fpgaminer]

You missed the salient word: "clear"

PayPal transactions never really clear. You can probably reverse a 3 year old PayPal transaction...

But Bitcoin payments are irreversible after only 1 hour. There are no other systems that accomplish that online.

[pedrocr]

If your definition of clearing is that they can't be reversed then nothing that isn't a crypto currency allows it. That's not the usual definition of transaction clearing though.