It became a mandatory monetary benefit in 1970, with an amendment to the Federal Labor Law, which stipulated that the bonus should be equivalent to at least 15 days of salary and must be delivered before December 20. In the constitutional article, it is referred to as a bonus although mandatory.
Full-time teachers in the state of Nuevo Leon receive an average of 50,000 pesos, current and retired. Keep in mind the 2 weeks is a minimum and many company employees receive much more.
If you read the link below the history goes back hundreds of years and for different reasons including the influence of the church.
https://www.milenio.com/negocios/breve-historia-de-cual-es-el-origen-del-aguinaldo