> But in NY, house sale records are made public but much to the detriment, many mortgage companies fake a bill for payment.

That frankly sounds more like a failure of enforcement, on top of a failure of the construction of the financial system. Here in Germany, it is absolutely not a common thing that mortgages or the banks holding them get sold like a hot potato towards some other sucker, and thus such a letter would cause immediate suspicion.

Here in Germany, founding a company creates a public record. There are a number of companies who then send all newly formed companies an invoice that looks like a legitimate invoice for expenses related to creating said company, but on closer inspection actually contain a dense paragraph of text that details that this is not an invoice at all, merely an offer you accept by paying. Quite possibly even a subscription

It's a well-known trick, our notary warned us that these letters would come and we should scrutinize any invoice for a while. But they manage to skirt at the edge of legality