It would be a very useful option if we could empty the trash with a double-click, or optionally another button like a middle click. Or also change the behavior of a single click, like: do nothing > open trash can > empty. And be able to do this for the other buttons as well.
I'm afraid this would be much too dangerous, sorry. Double-click triggering irreversible destructive behavior is something we could never do, not even if it was off by default. Single-click would be even worse!