That is because the green apple quickstep is not just a gringo problem. Bottled or canned anything is the safest way to get fluids. Unfortunately you suffer the consequences, obesity and dental caries.
I’ve traveled all over Mexico from an early age-mostly by car-to archaelogical sites, not to the “tourist” areas. I never had a problem finding bottled mineral water-Penafiel was a common brand-for myself, husband and kids, or diet Sprite, if anyone wanted it. People drink the sugary crap for the same reason they do here-they like the taste (gag!)