Because that seems pretty hard to swallow given how much people crow about Uber disrupting markets.
Uber does help define the landscape of drivers and availability. There are other sorts of pricing models they could even follow. Why not charge a little bit more during off peak times, and then turn around and incentivize drivers using the subsidy from off-peak hours, rather than dumping it all on individuals traveling during points of tumult/crisis?
There are a lot of models between the awful medallion system many cities have and the way that Uber works right now. And frankly as much as i hate how taxis work in a lot of US cities, and as much as i love the user experience that Uber delivers, they certainly should not be immune to criticism, especially over issues like this.