Belgian Economic Mission to Mexico
Mission happening now:

Taxis

In major cities, taxis are the most convenient means of transport, but some vigilance is recommended with respect to drivers, particularly in Mexico City. At the airport, only use authorized taxis whose rate (flat rate per zone) is set beforehand in one of the outlets located in the airport. In the city, rely on taxis booked from a hotel or a restaurant.

It is not recommended to hail taxis in the street. Uber is currently one of the safest and cheapest means of transportation in Mexico City.