I hear this a lot and it seems odd to me. I have literally never taken an Uber (which I admittedly don't use a lot when traveling) when I haven't been fully aware of and prepared to take a taxi as an alternative. When I have taken an Uber I just decided it would be cheaper/easier/etc. but, if an Uber weren't an option, I would certainly just take a taxi.
Taxis suck in a lot of places. It takes then forever to show up when you call, if they show up at all. Very inconvenient for eg. making your way to the commuter rail station in the suburbs.
