If I could press a button and have a car pick me up, take me to the train station, get on a train, and have a car waiting on the other side I'd choose that over the present litany of call a car, hope it arrives in time, get on the train, arrive at the station, wait around for a car. Many times I'm just too tired (or lazy) to do that, and call a car for the whole journey instead.

Same reason people who didn't take taxis take Uber.