Donald Trump, the New York billionaire real estate mogul and reality televison star stayed "under the radar"? Really, that's what your going with?
He stayed under the radar of the government. There's a difference between being a reality TV star and having the details of your finances under the microscope. The latter is happening in large part because he's now POTUS.
What looks like happened here is he had a $150 million loan. He paid off roughly $50 million, and the rest was forgiven. On those books, that forgiveness needs an offset, and it's to income. Instead of booking that, and alerting tax authorities, Trump formed another company that then "loaned" him $100 million, so on the hotel's books there's nothing interesting happening except the lender changed, but the entire debt is still on the books. But it's a fraud - the loan is just on paper, isn't real. That actually takes some pretty serious digging to figure out because the hotel's books look fine, and auditors if they examine it have to go to the fake entity and see what's on those books.
Bottom line is if you're willing to engage in tax fraud it can go on for a long time before it's caught, if the company is fairly careful. Here there's nothing on the hotel's books to raise a flag. From year to year, $150 million in debt goes to....$150 million in debt. Why look behind that if you're an auditor or the AG? Now there's a reason, and people have done it, and it's because of his high profile as POTUS.
Same thing happened with Manafort. His fraud was pretty blatant, but there was no 'trigger' to start an audit. Once he put himself in the public eye, in a huge way, and his shenanigans with overseas interests came to light, then there was a reason to look at his taxes and he got busted in a very big way.
For the elites, all this is a feature of our tax system, not a bug. They hide assets overseas and rarely get caught. Even when they do, the system allows them to fess up, pay their taxes and that's all we hear from it, so there's little reason to be honest. If there's a 90% chance of getting away with it, and if caught, just pay your taxes and a fine, why not try?