In the UK all of my cars have come via a dealer (in both cases whom we knew directly or via someone else), so they have a legal obligation to sell it HPi clear.
Aus on the other hand... one came from a mate, another came via a dodgy Pom, and the last from a guy out in regional NSW. New car in Aus is coming via a mate of a mate... it's all a bit harder as the reg plate don't stay with the car, you need the VIN to do the check properly.