Uber, the car-sharing service, has become ubiquitous. It’s now a multi-billion-dollar global business. It’s even become a noun of sorts — uberization — which people use to describe a disruptive change to a staid industry ripe for innovation (though, to be sure, the popularization of the word “disruptive” means that it is often used in ways that the concept’s author, Clay Christensen, didn’t intend).