This is part of the regressiveness of the US tax code. That’s a $40,000 transfer of wealth from those who cannot afford to own rental properties to those who can.
Not that I blame your friend for taking the tax break, I would too. It’s very hard to convince people to forgo benefits like that for the sake of society.
You are not wrong in general about the tax code favoring those with certain kinds of housing wealth.
But in particular regarding depreciation, the IRS will demand depreciation recapture at time of sale whether you actually took depreciation at any point in the property history or not. So if you don't want to pay double taxes you have to take the depreciation every year.
Not that I blame your friend for taking the tax break, I would too. It’s very hard to convince people to forgo benefits like that for the sake of society.