I was wondering how do these companies add these primary auto, revolving, and even mortgage tradelines to CRA's? Do you take ownership of the car or the house? Are they lenders, collection companies or people that figured out the system? Anyone has experience with these?
Don't really understand your question. As soon as you apply and receive either a credit card, mortgagr, or car loan, your history with the lender is automatically reported to either one, two and sometimes all three CRAs. Most creditors report the activity on a monthly basis.
99% don't. Most seem to just take money and run away. Assuming they could, it would be largely fraudulent. Think about it logically. How could you legally be added to a mortgage? Stay away from it. There is no reason for the risk and authorized user accounts are effective.