Why would my credit report look good on Equifax and not Experian?

My credit reports looks good for one agency.
I have a loan in really good standing that is being reported by Equifax on my credit report but when I look at the other, it has no history of the loan. Should this loan be reported to all three of the agencies?? Or is it up to them?

In order to work with a credit bureau, a lender must be a subscriber to their services and this costs money. The lender in this case only subscribes to Equifax. The bureaus only know what their customers report to them. They do not go out and do independent research.