Why are Mexican politicos uniformly light skinned ?
Racist hombres.
Old habits and perceptions die hard. Most Mexicans still think of their historic leaders from Spain when voting for the top office. Many Mexicans remain very opinionated on what the ideal person is supposed to look like.
Similar to some American Blacks, who separate people into social classes, based on how close they are to looking white. Not as openly as it used to be, but that custom still exists.
“Good hair”, meaning soft and curly or straight, vs kinky.
“A pretty complexion”, meaning light skin with subdued (European) features.
East Indians had an entire Caste System of social class based on these same physical features. If you look a certain way, you only get offered certain jobs. Darker skinned people got offered only the dirtiest jobs nobody else wanted.
For the same reason White Latin America are largely chosen in ; Cuba, Dominican Republic, Puerto Rico, Costa Rica, El Salvador, Guatemala, Nicaragua, Panama, Honduras, Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru and Venezuela.
Visit Mexico City and observe the proportion of the population sporting blond or red hair, faces with European features.