Isn’t that why you get a carfax????
Carfax ain't in the business telling people about the questionable history of cars because they actually care about people buying cars...
There are a number of ways to game a carfax report, and they do game the system. A lot of dealers get more used car business from online sales than in person sales, and they can get away with some "shortcuts" knowing that after you go through the process of buying a car, especially if you're not local to that dealer, you're more likely to drive it for a year and then trade it in than to return it.
A reputable dealer will let you take a car you're interested in to your garage (assuming you're buying locally to your garage) and have them take a look at it for you to give an assessment of the car's condition (a mechanic likely won't give you an assessment of price, but they will tell you things like "this was repaird, this is going to go bad within a year or two, etc...) .
Yes. Carfax is warning people to buy its services.