The key thing to understand is that commercial real estate is valued as some multiplier on rent (exactly the same as evaluating a bond by the interest rate it pays out). If the rent you're charging goes down then so too does the valuation, which can out you underwater on your loan and then you're just screwed.

Some kind of regulation that imposed an equation that increasingly devalues property from its last rented price the longer it remains vacant would do wonders here at correcting the market distortions. Another way to implement that would be to value vacant properties using the total rents charged over the past 5 years -- so the more vacancy there is in that, the more your total rent suffers.

Lenders can (and should) make this change too. It doesn't even need to be imposed top-down by the government.

Because they don’t care. The loan is collateralized and sold as a financial instrument and the bank is no longer involved. The loan holders should care but the loans are owned by hundreds or thousands of organizations and individuals who don’t have the mechanism to see what the underlying assets in their financial instruments are doing.

The movie “The Big Short” actually does a great job of showing this but for the 08 financial crisis.

The bank makes a loan based on what they think is likely to happen in the future, and you the borrow can influence that. You can say, I'm going to buy this commercial building in the highly desirable neighborhood, which has seen continuous growth for the past 10 years, and it will continue to grow for the next 10 years, so I can charge a rent of $X, which will support a loan payment of $Y, so you can safely give me $Y.

The problem arises when predictions about the future don't come true. Like a pandemic lowers the value of living in a city, so the amount of rent you can charge goes down. Do you admit that to the bank and let them change the terms of the loan (or have them foreclose), or do you pretend everything is fine, keep your asking rent high, and hope things turn around before the bank calls you?