bandits in the forest

This story was told me by a long-time French resident of Mexico:

A party of French tourists arrived in Mexico City and rented a car, intending to drive to the top of Popocatapetl, one of the two great volcanoes overlooking the city.  They did this even though they had heard reports of bandit activity in the forest that skirted the mountain.  And knowing this, they were not surprised to encounter a police roadblock.
    The police officer was cordial and business-like as he checked their passports and inquired of their purpose.  He then asked if they had any firearms, to which they said they didn’t.
    The officer’s expression registered amazement and concern.  Did they not know that there were bandits operating in the forest?  To travel unarmed was quite out of the question.  He could not permit them to so place themselves in such danger.  Without a weapon they could go no farther.
    The French were taken aback by this turn of events, and protested that they were strangers to the country and there was no way for them to obtain arms.
    The police officer considered their dilemma and said how much he appreciated their desire to see the famous Popocatepetl, but he could not see them endanger themselves.  Another officer came to the car and there was much discussion between them in Spanish and the second officer looked at them with sympathetic concern.  Then, as if an idea had occurred to them, the tone of their conversation changed to a happy good humor and the first officer announced that their problem could be solved.  By good fortune they had an extra revolver and for only $100 U.S. the officer would sell them the pistol and they could continue on their way. 
    Needless to say, the French had not expected such a resolution, but one knew that in other countries things were done differently, so they gave the officer a hundred dollars for the revolver and, amid warm wishes of safe travel and good voyage from the smiling and waving officers, they drove away from the check point.
    Several miles up the road they came to another police check point, whose officer, cordial and business-like, made the same inquiries as the first officer had done.  When he asked if they had any weapons the French proudly responded that they did, and showed the revolver they had just purchased.  The officer was aghast.  Possessing a weapon was so illegal that he could scarcely think of words to describe it.  He confiscated the weapon and sent them on their way.