I have no problem with what the Mexican man was doing. He's not getting rich or famous. He's not hurting anyone; he's providing a service that people need.

Also, how do you know for a fact that his people never burned sage? Sage grows all over the Western part of the USA and into Central America. Its scent announces that it's something special. Why wouldn't people in those areas figure out that it's good to burn for a blessing, and develop their own ways of doing so?

As for "Indigenous," -- I've heard a great many people refer to themselves as "Indigenous," especially on social media, where I get most of my Recommended Daily Allowance for human contact. (Sorry, I have trouble talking so I don't get out much.)

However, when you're traveling and talking with the local people, they would be more likely to refer to themselves as "Cree" or "Sami" or whatever. So, I guess it depends on the context.