Most dealer networks use autocheck now so if there is a service history it would be there.
Having said that many of those dealers simply do not. There is very little advantage. So, if there is a record its usually just mileage
but most mileage info comes from this.
Carfax mostly gets its info from insurances and public records. Very few shops report to them now. Like 10 years ago they managed to get lots of service info by blackmailing dealers and shops, but most have wised up and closed their doors.
In other words, it's all a load of ****. We used to clear car faxes on our vehicles before selling as they were never accurate (literally a letter from a lawyer which cost $200 would give $5,000 by removing nonexistent damage). So, what does that tell you?