In Mexico rural indigenous peasants were treated as subhuman garbage.
White landowners pretty much did what they liked: murder, rape, theft, kidnapping, forced labor, mass-murder, destruction of whole villages, forced relocation, ...
Within living memory, indigenous people would have their property stolen or destroyed by Spanish-speaking thugs with no legal recourse, would be forced into labor, would be murdered or raped on a whim by wealthy landowners. Until recently, indigenous people were not allowed in some Mexican cities after dark and had essentially no political representation. Etc.
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By contrast, in the USA we just killed all of the indigenous people and took their land.
The difference is that in Mexico & Central America the whole economic system was based on a colonial overseer class who used indigenous labor to produce goods for export, whereas in the USA the economic system was originally based on European immigrant settlers farming their own plots of land (or in the US South, based on plantations worked by African slaves), and indigenous people were economically extraneous.
The Catholic church also tried to destroy literally all indigenous writings in Mexico, and criminalize indigenous languages and cultural practices. So they had to operate in stealth. Some remain, but many things have faded from history and practice into myth.
It was too difficult, since it was easy for locals that knew the land to just run away and take refuge with other tribes. In Florida, some black slaves notoriously ran away and joined the Seminoles, a tribe that led a pretty notable resistance for sovereignty. This is a simplification, another big factor would have been the fact that many tribes had already established themselves as political entities, expect the five civilized tribes, via trade and intermixing. I would hazard that many white people from the south and southeast would have some native ancestry. Finally, when all blacks we're defacto slaves and free blacks were uncommon, it was easier to identify a run-away. In fact several Southeastern tribes owned slaves themselves and the Cherokee were actually split in their support for the Union vs the Confederacy.
When the Europeans settled in the Carolinas, they brought malaria with them. The ensuing epidemic affected both the natives and the settlers (and malaria, with lethargy as its major symptom, is especially bad for a manual labor force). People of West African descent tend to have a very strong resistance to malaria that's related (in a way I don't understand) to the sickle-cell gene. Since the ships trading back and forth across the Atlantic were also trading to the western coast of Africa (and exchanging sailors/slaves/passengers at all stops), eventually some west African laborers ended up in the carolinas, and someone noted that they were unaffected by malaria.
The eventual presence of large groups of west african laborers, combined with a tradition/economy of chattel slavery among the Carolina natives that predated the settlers to create a very economically effective slavery system that spread across the southern US.
South Carolina was founded as a rice-growing colony to supply food to the sugar-growing colonies in the Caribbean. They bought enslaved agricultural workers from west Africa because they had the skills to grow rice more effectively. Rice wasn't native to the Americas, so buying natives wouldn't have resulted in the significantly higher rice yields.
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sidenote: They also bought people who knew how to cultivate indigo for dyes. This meant that indigo was the dye most-available for the continental army in 1775.
White landowners pretty much did what they liked: murder, rape, theft, kidnapping, forced labor, mass-murder, destruction of whole villages, forced relocation, ...
Within living memory, indigenous people would have their property stolen or destroyed by Spanish-speaking thugs with no legal recourse, would be forced into labor, would be murdered or raped on a whim by wealthy landowners. Until recently, indigenous people were not allowed in some Mexican cities after dark and had essentially no political representation. Etc.
* * *
By contrast, in the USA we just killed all of the indigenous people and took their land.
The difference is that in Mexico & Central America the whole economic system was based on a colonial overseer class who used indigenous labor to produce goods for export, whereas in the USA the economic system was originally based on European immigrant settlers farming their own plots of land (or in the US South, based on plantations worked by African slaves), and indigenous people were economically extraneous.