Uber isn't a cash venture, and several activities in the US require either a credit card upon which temporary authorizations can be placed, or a full (and sometimes, over-)payment on a debit card, the difference being that the debit card isn't backed by a line of credit that becomes due in at least 20 days, but rather it is spent directly out of a checking account.
You need this for:
- gas stations
- hotel stays
- car rentals
- sit-down restaurants or bars
The SV/HN is out of touch argument doesn't fly here. Rather, there is a wide gulf in the spending ability and access to services between a US credit card owner therefore a participant in the mainstream banking system, vs. someone with only a checking account, vs. a person who can't qualify for either and conducts their affairs with cash. This is a problem much older and much more foundational than the Bay Area vs. everyone else and the techies and non-techies divide, and is a significant delineation between the US middle class and lower class.
Is ride-sharing that big of a cost for your day to day?
For a lot of people, it is. The only people I have ever heard say this kind of thing, at least from my experience, are middle-class and well-off, or better. This cohort is the exception, because the norm (especially among millenials) is check-to-check living. $25 is several days' worth of food, two weeks' coffee budget, the price of a full tank of gas for a small car, or numerous other things to many, and $25 can be the difference between your card going through or being declined.