A: No. The walkie-talkies you purchase in the U.S. or Canada, operate on assigned frequencies established by the U.S. & Canada FCC. The problem is that Mexico has assigned these frequencies for other usage and therefore your walkies could possibly interrupt local communications [this is the official version of the story – read The Grey Area below].
People who use them can be subject to a fine and confiscation by both the police and military.
That said… walkie-talkies operate at quite low power and the chances of being stopped and having them confiscated are correspondingly small.
If you get a red light at customs then your bag may be inspected. If the agent finds your walkie-talkies they may be confiscated.
Follow these guidelines if you take walkie-talkies to Mexico:
Pay close attention to whether they receive any broadcasts from local agencies before actually transmitting.
If you hear anything over, perhaps, a half-hour of just listening, don’t transmit on them.
Do not openly use them in public [your hotel/resort is okay].
THE GREY AREA
Many people do get their walki-talkies through customs, even with getting their bags checked. We have also used walki-talkies in front of the military without having them confiscated.
The Mexican government does not confiscate walki-talkies because they interfere with official radio channels, so we have been told. They confiscate them when there is unrest with the EZLN [Zapatista – Freedom Fighters]. Basically they do not want modern communication devices in the hands of the EZLN.
For example, if you go through a military check-point wearing a Che T-shirt, and they find walki-talkies on you, you will get hassled and they may get confiscated.
If you are on vacation to an All-Inclusive resort with your children you usually will not get hassled, but, you never know. Mexican military and police are totally unpredictable.