I remember when my Dad was pulled over by a local cop between Mexico City and Cuernavaca. My Dad had put some pesos in his wallet where his license was and the cop took the money gave him back his wallet and we were on our way!
Another time, going through customs from the States through Laredo, he had some industrial diamonds in his suitcase for the company he was working for. So, he put a small AM/FM radio (this is during the sixties) in the suitcase, inspections took the radio and we were on our way!
That’s how life was back then.
Useful phrase: "Officer, may I pay my fine to you now?" The mordida was usually reasonable.