Why .ajaxError and friends are not static functions of jQuery?

Why .ajaxError and friends are not static functions of jQuery?

I don't get why .ajaxError and friends which are basically custom events are coupled with dom elements.
  1. // why should i bind to document, if i don't need it
  2. $(document).ajaxError(function() {
  3.       reportError()
  4. }
especially given that reporting to dom would be still easy the other way around
  1. $.ajaxError(function(){
  2.       $(".msg").html("ajax error")
  3. }
Anyone can explain?

Thanks,
Federico