Can you tell me more about that? I am only using a local database (with GenealogyJ) and I don't have any experience with online databases like ancestry.com. How is your dad using it? Do the people he's paying directly enter the data online?
Not OP but the payment bit sounds like when you pay a local records custodian to do a "search", ie look for all the Djikstra family members in the period 1700-1800. They then look through books (BMD - baptisms/births, marriages, deaths/funerals) in the church building (or wherever) and compile a list of the data.
Often novices can't read the writing, and when the records are in another country/region it's easier to pay someone. Also, many records can only be searched this way, the public don't have access.
There are enough people who do it for a hobby and/or religious purposes that it seems like a pretty viable subscription model.