But Maloof did make an attempt to find relatives and could find only one who he made a deal and paid them $5000. So he did his "due diligence" although everyone can have their opinion of how much that should be.
No, it isn't a matter of everyone having their opinion. It is a matter of what the common law, statute law and case authority has determined how much that should be.
If you have a problem like this, you go to a lawyer who is experienced in these types of issues, who will then take the facts that have been gathered so far and make application to the Probate Court for directions. John Maloof would have difficulty doing this himself, but with the cooperation of that relative he found, he could start the process in the name of that person.
You would use the Court directions to determine what level of genealogical investigations was required, but it would not necessarily have to be an endless search.
These are the sorts of things that the Court is used to. The Court would use its equitable jurisdiction to balance the interests of bringing the situation into completion with the competing interests of the located and not yet located intestate heirs. Their are all sorts of tools available to do that, while supporting and encouraging the realization of assets.
Its true, to make that happen, you need money behind you.
If you get that money in place, and do things right, most of the controversy disappears. The estate can then contract with John Maloof to make use of his negatives and his services. Much more Vivian Maier photography can then be released to the world, Mr. Maloof can make a large but fair amount of coin and the intestate beneficiaries can enjoy a windfall.
Any fees and expenses charged by any of the lawyers would normally have to be approved by the Court before they were paid out of the estate.
All of which would have been avoided if Vivian Maier had made a simple Will giving everything to whomever she wished.