> The Spanish attempted to coopt and convert the local population,

Population densities in Mexico and throughout much of what is Latin America were considerably higher than in the North.

Also IIRC the number of Spanish colonists who came to the Americas during the 17th century is about the same as the number of immigrants to the English colonies on the East Coast. Considering how massive the Spanish empire was there just weren’t that many Europeans there. Trying to subjugate and assimilate the natives was really the only option they had.