No real argument there - although I have never heard of a specific "drone tax" in Mexico and I am still skeptical such a tax exists (has anyone else heard of that?)...if it's not simply a shakedown (quite possible), it may just fall under the "import duty" that's sometimes (but not always) imposed when bringing in any fancy or expensive-looking cameras or other perceived high-value gear. I'm very curious to know if this is a specific fee/duty/tax/whatever on drones, or just the more general (and long-established) practice of "you have something expensive, so pay us some money".
According to this thread,
A look at Mexican drone laws, while yes there definitely are some (surprisingly) tight restrictions on larger drones and commercial use,
if you are just flying recreationally and you have your sub 250 gram Mini along, even foreign visitors are OK to fly drones with no registration or permit required (with some reasonable location prohibitions/restrictions) - at least that's the best I can make out of the contradictory writings posted online (here and elsewhere).
I agree that it's important to research drone regs before visiting foreign countries, as frustrating and murky as that may be (and as someone who enjoys internatonal travel and photography, it's a pet peave of mine). Unfortunately, much (most?) of what one finds online about foreign drone regs is way out of date, contradictory, or just plain wrong.