Actually, I knew quite a few people that was brought in from door to door work. This includes my own mom, the sister that studied with me, and quite a few others. I do agree that most are from informal witnessing, such as family or friends, etc. But even though most consider the door to door a waste of time, they do still get a lot of interest that way.
I actually respect the fact that they still go door to door, even though, yes, it can be annoying. It is an important part of freedom of religion, and speech, etc. And even if most nonJWs DO NOT agree with it or appreciate its value, if they are stopped by government, then what freedom of others will be infringed upon next?
When I went door to door, we all ignored the signs that said, 'no soliciting' because we reasoned we were not selling anything, so it did not apply to us. How arrogant is that, haahaa! I suggested to one nonJW friend a few years ago that she replace her sign with one that specifically referenced JWs. Maybe THAT would stop them, haahaa!