Sure, if you are white (or even black), the Mexican consular employees will charge you more to overlook some of the obvious errors in the documents you "rented" in the parking lot, but the extra dollars are well worth it. If you ever spend time in Mexico in the future, you'll be able to claim an additional social security benefit in the name on each of your matricula cards.
You would have shown this card to the cop. He would have seen you were doing nothing but would record your information on his computer before telling you to move on. The computer entry would be part of your proof in Mexico that you were here, working, but your boss wasn't remitting payroll taxes.