About the only thing I'd use a Carfax report for would be emergency toilet paper, so I really wouldn't care what it said. Why bother reading it when its 100% known to be inaccurate?
And it would appear that even dealers that do participate don't necessarily participate all the time with every service / repair, just when they feel like it I guess.The family members car I pulled history on was bought new and had only ever been to one dealer, some of the services/ repairs from that dealer where on the report , but a lot wasn't, same dealership everytime, dealership wasn't sold, not rebranded, didn't change management, heck it's still at the same location with the same name today.
Leaving big gaps in information leads people to wrong conclusions anyway (i.e. oh look, report showed they went 20K miles between oil changes, when in fact there were two oil changes in between there missing from the report) and DIY entered stuff is exactly the same thing as saying "I took really good care of it", they're just doing it electronic form ( I mean if you're gonna just believe them without proof because they typed it into the internet and it shows up on a carfax report, then them saying it verbally to your face carries the same amount of evidence).
No information is better than wrong information IMHO. If a seller wants to prove service history, hard copy receipts are the only way.
...