Uber has network effects. It's definitely possible and inevitable even that they won't be on top anymore at some point, but what they are doing is not exactly a commodity if it relies on a dense two-sided marketplace.
While it does have network effects, I'd argue it's not recession proof (mildly cyclical, even), and there's low switching costs to using other forms of transport (for example, I haven't used Uber in lieu of Lyft / driving my own car and had no issues)
Uber has shown great growth in markets during recessions: ex Brazil. The theory is that ridesharing is a driver constrained market, and during recessions, more people drive for uber to make ends meet. Also, people invest less in large purchases (cars) and instead spend more on services with a higher marginal cost (taxi, ride share.