I just spent a week in Cozumel, and used taxis exclusively. 100% of the drivers quoted the official rate in pesos. The dollar rate was approximately: round (typical, not bank) pesos/USD in favor of driver, calculate dollars, round to whole USD in favor of driver. Which I found very fair.
This was different than my trip about 10 months ago, when it was not uncommon to be quoted wildly inflated rates. As far as I am concerned as a customer, Uber has done the taxi drivers a favor. Taxi's are so ubiquitous that they are more convenient than Uber and, now that the rates are honest due to the competition, I think they might be cheaper (in any case, they are definitely reasonable now).