I don't know. Maybe I'm not the target market, but I often think "hey, I wonder if i can get something a little nicer.." and then am blown away at the multiples of price.
For SUVs, usually it's been considering a ski trip or something, so, yeah, I can see where people are "stuck".
I use Sixt whenever I can because they actually have nice european cars. Hit or miss in the US (I once got a Camry when I was trying to get an Audi A3; the Camry's a bigger car of course but I don't need a big car).
Flew into Seattle once, got a massive brand-new Volvo S90 sedan with all the bells and whistles for like $60 a day, same price other places wanted to charge me for a Camry. I'm sure if I had asked for a Cadillac from Hertz it would have been $400+ a day, and less desirable to me. shrug