Buses don't care about anything! Whereas the drivers almost fall asleep in Veracruz, in Merida they try to set a new record in crossing the city north to south, frightning as many people as possible. Try to spend as much time as possible on the zocalo, no buses allowed there. but it's part of the experience ;-)
Be careful by going on the top of the PYRAMID OF UXMAL. The stairs are very small and the way up is also very steep !!!!