personally i feel this is bordering on infringement on the rights of the businesses.
Do you consider any car and its contents parked on your property to be under your control? There is a line that needs to be drawn, where does the business's property end and the individual's property begin? Where it is parked, how long it can stay there, and the intention of parking it there are as far as I would give a business owner. However, the right to the car itself and its contents should be solely the responsibility of the owner of the car. Wouldn't you agree?
Not really. Businesses have the right to have cars on their property searched. That is why companies can hire private security and inspect cars, with reasonable motives of course.
The individual's property begins on the individual's property or in the public domain. But within the property of another individual or group it is certainly not considered free from regulation by the property owner.