How We Got United to Waive the Tourist Tax on my Dad's flight to Mexico since he's a Mexico resident
In my experience flights from the US to Mexico charge a Mexico Tourism Fee unless you're a Mexican Citizen and list your citizenship as Mexican when booking the flight. However, for the rest of the people who should be exempt this does them dirty. When you google what the official name of that tax is in Mexico, it's called DNR "Derecho de No Residente". It literally calls out in the name that it's for Non Residents!
So if you're a resident but not a citizen, what are you suppose to do. It's just that the US airlines have not taken the time to create a more sophisticated way to note the proof / reason why you are exempt.
In my Dad's case, he's a permanent resident. So we called the United agent and explained the situation. I told her the tax is actually called DNR "Derecho de No Residente" or "Visitor Non Resident". I also mentioned I had found the information on a Mexican government website. I offered to share the information. She could not receive an email, but she was patient enough for me to verbally share the entire link. She reviewed the PDF on the site (Page 3, second paragraph is where it states Temporary and Permanent residents are exempt).
She asked us to hold and said she needed authorization from guest services. After a few minutes, she came back and said she could go ahead and waive the tax. At least the time we put in gave us the result we wanted. Hope this helps others.
Here's the PDF link: https://www.gob.mx/cms/uploads/attachment/file/565926/Ingreso_de_Extranjeros.pdf
Worth mentioning, if you read page 3 of that pdf, there are even more reasons you could be exempt from that tax. Check it out.