I'm not sure what you mean by it not working. I haven't tried but they're a regulated system, are you sure it's not on your end? Have you been reporting your capital gains and losses over the course of the transaction on both sides? If not the tax authority may have some serious questions for you.
And why wouldn't I make negative assumptions of crypto [1], [2], [3], [4]. There's a scammer at every single level and being intentionally resistant to censorship, control and authority makes that impossible to stop. It's designed to support scams.
Remember the man who lost $420,000USD while attempting to use Quadriga to exchange USD for CAD when moving to Canada using exactly the approach you're describing? [0] It's like asking me why I've got negative associations with the "Titanic II." Something about what happened to the first Titanic.
Last, based on my research, it appears Mexican crypto exchanges aren't regulated yet, and that regulators are about to shut them all down [5]. "Because cryptocurrencies are such complicated technologies, the argument goes, average citizens can’t understand how they work and should not, therefore, be allowed to buy them." I'm 100% with your regulators.
[0] https://www.bloomberg.com/news/articles/2019-02-09/software-...
[1] https://www.theglobeandmail.com/business/article-gerald-cott...
[2] https://www.chepicap.com/en/news/4366/roubini-on-tether-it-s...
[3] https://www.theverge.com/2018/3/22/17151430/bankruptcy-mt-go...
[4] https://www.forbes.com/sites/cbovaird/2019/03/22/95-of-repor...
[5] https://coincenter.org/entry/new-regulation-would-effectivel...