In South Florida, it's due to monopolistic practices. The main player sets rental rates based on "market rates", which is laughable, They ARE the market.
And for $1450 a month, up from $900 just four months ago, you get a 50 year old rusty metal box with roof leaks, no insulation, substandard electrical, rolling doors that fall off the tracks, and more. Oddly, there are brand new Cat 3 hurricane rated hangars that rent for less money nearby. But that airport is one of the few that doesn't have the big players running things.
The game plan is to jack prices to drive out the little guys, and then claim there's no demand for tee hangars. Then they demolish them, and put up large jet hangars. The cities are all onboard with this, because they get a cut of the fuel sales. And they'll sell a lot more fuel to a Global Express than to a Mooney M20C.
And after the crazy rate increases, there is more turn over, and more empty hangars. Many tenants are still at the airports, but they've out on the ramp now. So it's not really true supply and demand. It's extortion, using our tax dollar supported airports against us.