It sounds as if Trump’s $1 billion tax deduction was very unusual. According to Fortune, it depended on his running his business as an S corporation, and on complex tax laws dealing with S corporation losses before 2002, when the provisions Trump used were eliminated. They allowed an owner to personally take advantage of losses that were actually incurred by his creditors and suppliers.
I don’t understand the reasoning behind this provision, but apparently other people did not either, since it was later repealed. I suppose it was something like bankruptcy law, allowing a company to stay in business that had incurred huge debts it could not pay. Congress apparently decided (correctly) that this was too generous.