You seem very confused about the B visa process, or at least conflating it with K-1. It’s not at all similar. There is no petitioner.
COs have discretion to consider printed supporting evidence brought to the interview, but they are not required to. The online application (have you looked at it?) is quite comprehensive. It asks for all pertinent biographical info about the petitioner. Documents such as property deeds or professional licenses are fine to bring along, but because such documents are frequently faked, their usefulness is limited.
And the burden to show no immigrant intent is entirely on the applicant. In other words: the consular officer has neither the time nor scope to verify the credibility of information brought to tourist visa interviews.
Yes, it does suck for some, but it is 100% the result of people who abuse the system/perpetrate fraud/have a miraculous change of heart at baggage claim, and decide they want to stay. Like Boiler said, it is what it is, and for good reason.