NASA keeps the original film negatives from the Apollo program sealed in a frozen vault in Houston, TX and rarely grants access to them. As a result, nearly all of the photos we see of those historic missions were made decades ago or are copies of copies. Recently, the film was cleaned and digitally scanned at “an unprecedented resolution”.
It’s my understanding that any photos NASA takes are considered public property so long as they don’t contain anything covered under ITAR or otherwise classified/secret technology. Surely this would include any images being sold to the public, since they’re obviously not containing classified material? I agree this is strange if they’re only being made available for purchase.