I qualified as a London cabbie in 2015. Back then, most of my work came from people hailing me in the street, and cash was still king.
In fact, I only had around four months of driving like that before card payments became mandatory. A couple of years later, the taxi apps really started to take off, and the job began to change.
These days, around 60% of my work comes through the apps. The rest is split between card payments and the occasional cash fare.
It's amazing how much the trade has changed in such a short space of time. Personally, I think it'll eventually become almost entirely app-based, although only time will tell.