BTW my wife rents retail space at a shopping center and even though they have 20% of their units empty, they refuse to lower the price she negotiated five years

BTW my wife rents retail space at a shopping center and even though they have 20% of their units empty, they refuse to lower the price she negotiated five years ago (her lease is up for renewal). She called a few other places and they're also still charging the same prices and don't seem willing to negotiate. What's the deal with that? Shouldn't prices be going way down since there's so much empty space everywhere?