I remember when I bought my first laptop. I was so ignorant...that I bought a laptop just to get "free" internet anywhere I was in the world. I actually thought I connected to some satellite in space to get my signal...and this service was free just because I bought a laptop. And apparently I'm not the only person who fell for this theory.
To answer your question about how many people connect to the wrong Linksys while their at home...I'd imagine its a frequent happening. Why?? Because when I first started playing with my first laptop,...I connected to my default Linksys AP...and then later on that night I saw another Linksys AP when I rebooted, and yes I connected to it instead of mine. Not intentionally, but because it was an open AP (like mine at the time) and Windows picked it because its power level was stronger than mine. (I was outside in my backyard having a cold brewski.)
So yea..I think it happens quite frequently.