Oaxaca has an adequate service of public transportation, which is based or rather sustained by the bus lines (camiones) that cover the most important streets and avenues of the city.
These units follow a predetermined route, and their tariff is pretty economic; although, sometimes its pace is too parsimonious; therefore, they are not recommendable when travellers are trying to beat their clock.
The offer of urban transportation is complemented with the service provided by the taxis; a faster and more direct alternative to move from one place to another. Make sure you check the taxi driver's identification before boarding the vehicle.
Likewise, prefer the units that are parked in front of the hotels and lodges for your own safety.
On the other hand, you will, find bus terminals with vehicles bound for the airport at the main tourist destinations of the state, such as the Bay of Huatulco and Puerto Escondido.