That, I think is the key question and no data is given. IMHO, I really doubt Uber has expanded the market, but instead taken a share of it, so 'creating' 20,000 jobs is at the expense of X thousand others.
I think without a third-party assessment of reliable data on the market every opinion on the subject is based on FUD. Unfortunately, at this time we seem to be missing both reliable data and an "objective" assessment.