Ask a surveyor with experience in Mexico.
It looks like most of the minor streets are mostly parallel with or perpendicular to the major road to the north and the rest are aligned along the cardinal directions: north & south, east & west. Lots of the properties and their respective drainage and road right of ways were probably apportioned to align with whatever the most significant roadway or canal was in place at the time. I can see the being portioned off using simple legal language like you can buy the north 50 meters of the south 300 meters relative to “this road” and the east 50 meters of the west 200 meters relative to “this canal”. You can accurately divide an area this way without any need to define a grid north, a proper grid coordinate system, and very basic survey tools.
I’d guess that the other streets oriented to the cardinal directions came later as survey tools and practices advanced or some other change in the way municipalities regulate. For example, in the U.S. you see most gridded streets and lots in older areas, relative to sections townships and ranges, but in new platted developments constantly curving streets are all the rage.
Whatever the cause, you are seeing the history of land development as the area develops it’s customs around land development.
“Boring straight lines” as you put it are also a way for the poorest land owners to describe, subdivide, buy, and sell property using simple easy to understand language, often without even the need for a surveyor or a lawyer to get involved. Curved boundary lines are a clear indicator of commercial development at the higher end of that spectrum. Ordinary folks are not going to have the necessary training to do anything to directly subdivide property described in that way without involving lawyers and surveyors.
Moreover, you often can’t sell a property without ingress and egress access to some public right of way. The same rules for simplicity of geometry apply to those right of ways too. Curves are vague and require complex legalese to describe in words. It also wasn’t too long ago that the precision of survey tools just did not exist to accurately describe parcels as anything but straight line distances with sometimes VERY vague information about orientation. Only more recent subdivisions (often much less than about 100 years old) include curves described with any decent level of precision. When they do describe curves on older documents it’s almost always in reference to large curves along existing structures (like railroads) and the actual geometry of that curve is not fully defined.
What we see here is only tangentially related to tourism in that it is directly related to the entire business of land development, which includes everything else.