>I've often thought something similar about wheel-clampers. As pay the £100 to get your car unclamped you mi's well by a huge pair of bolt cutters and cut it off. Then you still have the tool to keep. Do they do wheel-clamping in the US for illegally parked cars (*not the police, council, but independant contactor firms)?

Haven't seen them here. Usually anyone who owns a parking lot (be it a shop, or someone who rents space for apartments or offices) has a contract with a local towing company, which then have the duty to check whether all the cars on it have the sticker or other sign of eligibility. Then they just take your car away, and you have to pay them for the service of towing and guarding your car (even though they specially guard it against you :). Costs anywhere between $50 and $120.