I got stuck once in the middle of the day in a million plus sized US city (not Dallas) where every single cab company I called just flat refused to get me anything within the next hour, and no promises after. Just nothing. No public transport that went where I needed to be, of course. Since I was there for work, I luckily had a phone number of a coworker (whom I never met before) that I had to call and beg to rescue me. Never had such situation once uber/lyft came up.