Some of the places I fish it's a problem. Most of us have 4 wheel drive that fill the fishing parking areas. They like to get under the trucks and punch holes in the tank to get the gas. That's been going on for some time now.
Lately the private road I live on has had problems with gas siphoning. I live near the end of the dead end and have had no problem yet.
I had a friend (a girl who was 19 at the time) and put ethanol in her tank even though it wasn't a flex fuel car. She thought, "hey its cheaper, I'll buy this E-85 gas". Of course her car died on her later on in the day and had to get it towed...before she could do that she had some guys push it to the side of the road and she left it there for a whole day before calling the tow truck (b/c she's a dum dum) anyway when it finally made it to the dealership for work they said there was no gas in the car and it just needed an internal cleaning with some simple chemicals.
Whoever siphoned her gas was in for an unpleasant surprise.
Siphoning happens in IL from time2time...in the rural and urban areas. Never heard of it in the burbs though.