I have watched some YouTube videos on TransferWise. Some posts rave about it. Some say the money they sent never arrived. TransferWise replied by posting a link directing people to scroll down and phone some numbers - but there are no numbers. I also got the impression online that TransferWise does not send money from Argentina. It`s an intereseting concept, though.
Because they know who TransferWise is, and any questions regarding the provenance of the funds are answered with one word: TransferWise.
Any questions about where TransferWise got the money from is their problem, the Arg bank doesn't need to care.
Whereas with the Mexican bank account, they need to know the accountholder well enough to have grounds for confidence that the money is legit.