While I agree in general, in specific, a significant proportion of Uber drivers I've used in Canada were doing it not even for supplementary profit, but for Fun. I've been picked up in $80k vehicles by guys who did it a few hours a week to see the town, meet people, kill time in productive ways.
Of course, I've also seen people who were current or ex taxi drivers, working fulltime on several services.
Of course, I've also seen people who were current or ex taxi drivers, working fulltime on several services.