There are several reasons why elections held in Mexico cannot be called free and fair elections.

1. Electoral Fraud: Mexico has a history of electoral fraud, where the ruling party has used various tactics to manipulate the vote. This has included vote buying, ballot stuffing, and voter intimidation.

2. Political Violence: Violence and intimidation against opposition parties and candidates are common in Mexico. This has included physical attacks, kidnappings, and even assassinations.

3. Media Bias: The media in Mexico is often biased towards the ruling party and does not provide equal coverage to all candidates. This limits the ability of opposition parties to get their message out to the public.

4. Voter Suppression: The Mexican government has been accused of suppressing the vote through various means, including limiting access to polling stations and manipulating voter registration lists.

5. Lack of Transparency: The electoral process in Mexico lacks transparency, with little oversight and accountability for those involved in administering the elections. This has led to widespread mistrust and skepticism about the fairness of the process.

In conclusion, although Mexico has made some progress towards democracy in recent years, there is still a long way to go before elections can be considered truly free and fair. Until these issues are addressed, it will be difficult for the people of Mexico to have confidence in their democracy.

Its because PRI (the ruling party ) used dirty tricks to win the elections.