Memories in Mexico ～ the problem is......

As you can see, I went to many places and ate many kinds of Mexican food. The people are so nice and very kind to me. I had a great time there. Let me say this trip is perfect! But I can't say that , although it is so pity. After thinking for a while, I decided to write one thing which made me so disappointed, because you may be ready when you go to Mexico as a tourist.

When my mexican friend and her parents took me to the mexico city by car. As my friends father asked a policeman to show the right way to the mall, it happend. When he spoke to us, eeryone looked upset. (of course I couldn't understand at all)
They are trying to say something to the policeman, and my friend made phone calls to relatives.. It was so nervous moment. Guess what was mattered with us??

I don't know exactly. In Mexico city, the authority limited driving car by the last number of their car number plate for the air pollution. For example, if you have a car with a number plate xxxx1, so you can't drive on Monday until 10pm. To our unluckey , the day we enter Mexico city was the very day we were not allowed to drive inside Mexico city. Actually we didn't know that, I mean my friends knows the rule, but didn't know details. Before and after we entered to the city, we never saw
any sign about this rule.

Well, the policeman found my friends car number, he asked us the money in bribes. Of course we broke the rule,but.... In whole my life, it was the first time such a thing happen to me. I have read the books and articles about mexico. So I knew about this. My friends were so angry and upset. Me, too. I felt so sorry to them , because I went to Mexico, they took me to the travel. I asked them they can call the authority about this. But they said it would be a waste of time. It happen everywhere. It was so pity. The problem is ... how will they improve?? How do you think?