This is intentional for the art style. In Mexican Muralism, the indigenous identity of Mexico was being displayed in public in the buildings of the colonizers.
“Many of the murals from the muralist project took on monumental status because of where they were situated, mostly on the walls of colonial era government buildings and the themes that were painted.[5] The mural painters of Mexico freely shared ideas and techniques in public spaces in order to capture the attention of the masses.”
“Many of the murals from the muralist project took on monumental status because of where they were situated, mostly on the walls of colonial era government buildings and the themes that were painted.[5] The mural painters of Mexico freely shared ideas and techniques in public spaces in order to capture the attention of the masses.”
https://en.m.wikipedia.org/wiki/Mexican_muralism