> How else do you get what might be illegal products off the shelves?
Your premise is that there is a difference in the product.
The product is a piece of hardware that connects your phone/laptop to the car's computer. Are you using it to program the computer to bleed the brakes, or are you using it to program the computer to defeat emissions tests? It's the same hardware dongle either way. A roll of duct tape isn't a different product when it's being used in the commission of a crime.
You can try to prosecute companies that actually ship the thing with software to defeat emissions, but that doesn't really do any good. People would just get the generic hardware from the store and the defeat software from anonymous third parties over the internet.
If you actually want to stop it, try one of these: The old style emissions tests, where they put the car on a dyno with an exhaust probe, have been mostly phased out because the equipment is a lot more expensive. Keep some of it around. Then when someone goes in for their emissions test, roll a D20 and if they get a 1 their vehicle is taking a trip to the full service facility and if the exhaust probe says something different than the car's computer their car gets a free forensic analysis to check for a defeat device. Finding one means jail time.