Taxis were a cottage industry - pretty much the opposite of a cartel (so were Bed and Breakfasts, another "app-disrupted" business).

Could you tell me why you think that?

In NYC, prior to Uber entering the market, taxi medallions changed hands for up to $1mm. Prices were fixed by the TLC.

If these are no strong indications of a cartel, I don’t know what is.