I'm not sure Uber as a middle man disqualifies the contractor status completely. (Other things might, though.)
Compare to a sub-contractor in a web design gig. UberConsultCorp contracts with the client, takes their money. They call me to do some WordPress plugin work and pay me for it, of course retaining a cut for themselves. No question I'm a 1099 contractor, but I may not have had contact with the real "customer" nor could I have done the work without UCC farming it out to me.
The time & place situation muddies the contractor status, but that's not unheard of in 1099. "I need this done by 5pm!" is still a valid 1099 gig. (You can bet you're getting my "you pissed me off and I don't like you" rate, but...) That's the time covered. Say I'm contracting to do hardware maintenance for a company, then it's, "We need you here by 5pm!" Time & place, but still clearly contractor status.
I'm not sure the negative consequences of declining a gig necessarily hurt the 1099 status either. If UCC calls me up and I decline the job, it doesn't seem unreasonable that they'd look to find more dependable subs in the future. Their choice to call someone else next time doesn't mean they "fired" me as an employee.
I'm not sure (other than nanny state, etc.) why there's such a push to re-class Uber's activities. If you could show me a rash of drivers being harmed in such a way that being "employees" would have protected them, maybe I'd feel differently. As it is, it seems like there are a large number of drivers content to work as contractors and Uber is obviously willing to pay them as such. It sounds like consenting adults conducting mutually beneficial business. (Unless you paid $1,000,000 for a NYC hack license, then I could see why you'd want to do everything you could to disrupt Uber's business model even though you're not really a party to it at all...)