Have to disagree. If you're being lazy, buy frozen chopped onions. As long as you're not going to chop more than two onions, a kitchen knife will be faster than a chopper. Also, I hate monotask-tools. They sit in the drawer taking space 95% of their life.
The worst part of chopping an onion is removing the skin that always falls to pieces and makes a mess that's hard to pick up. I don't see how this solves that.
For one, never thought about it. But now that I am I'm 6'5" and my trash can top maybe comes up to knees, sounds pretty miserable. I guess I could get a bag and set it on the counter though.