Pre Delivery Inspection

Bought our first used campervan from a major dealer.  It wasn’t until a few weeks after purchase that I realised we had no record of the PDI (service and hab check).  I called the after sales office and they emailed me a certificate which simply says the PDI had been done.  I have asked them if they could send me the exact details of what had been done for the PDI,  they refused saying it is an internal document and we are not entitled to it.  I might be wrong, but I can’t understand why the full PDI documents are not available to the customer who has bought the van.  Does this happen at other dealerships?