Our guess is most people don't know what to do with old, out-dated computers, television sets, cell phones and other electronics.
Our bet is most people simply toss them into the garbage can. Others take their old TV's out on some old county road and simply toss them out.
First off, it is technically illegal to put old electronics in your garbage can. Will the electronic police ever question you, we doubt it.
The reason they don't need to end up in a landfill is that electronics contain hazardous materials, whether it's batteries or other components. If they end up in landfills, at some point...