If I could just offer a little professional insight here, as a civil engineer who specializes in transportation:
Others have already pointed out the urban areas in the US where public transit is viable and readily available. I live near one of them, and still, I have to walk between a half hour and an hour to get to the nearest bus or train station. Although some outside and inside the US might enjoy thinking that this is because Americans are car-crazy and public transport-hostile, the reality is that the US is a geographically very large and overall sparsely populated country, in almost all of which, public transit systems are not economically viable. According to
this website, for example, the United Kingdom, overall, London and all its other cities and all its rural areas combined, is the 50th most population-dense country in the world; France, the 100th; Ireland, the 135th; the US, 176th.
Now back to your discussion of Uber in London, already in progress.