I blame Microsoft, their OS automatically connected me to the best Wireless connection without my knowledge. Hell, I thought free internet came with XP.
You evidently don't use Windows, because it forces you to choose a wireless network the first time you use your wireless card or any time it doesn't find a previously-used wireless connection.
For example, I have the wifi network "PavezaHome" in my house. I also pick up my neightbor's signal, "1YOBABYSAM". The first time I run a wireless card, it prompts me to pick one. If I disconnected my wireless router and turned it off, it wouldn't automatically connect to "1YOBABYSAM".
It was a cute stab at Windows, but ultimately failed.