[Faceman]

While the "possibility" of all the information being free for every law employee is indeed troubling it is clear why eBay employs certain strategies to catch thieves or frauds.
Like any real auction house or merchant eBay has to ensure that nobody gets hurt while using their service. If someone for example buys a stolen car and gets in trouble he's probably going to complain to/sue eBay.
This is also where the scanning of "unusual behavior" comes in. It is a well-known strategy of frauds on eBay to build up great ratings by selling cheap stuff (like tickets, books, CDs,...) and then switch to really expensive stuff (cars, laptops,...) which they cash the check for but don't deliver.
The really troubling issue is the cooperation with any law official without a court order. This carries the possibility of misuse as any officer can request information and use them for non-legal purposes/personal gain (e.g. by selling them). This also is the main reason why a court order is normally required for such investigations. Any sane and law-abiding person will cooperate with the police if an officer comes by and asks some questions explaining the nature of his investigation, but few will instantly send the information without asking after receiving a short fax signed by an officer.