This was not unusual with Mexican American babies back in the 70's and 80's. I wouldn't have paid much attention to it prior. However, the children always appeared extremely cared for and loved.
was common with Italian/Greek babies too - where I lived as a child there were large numbers of Italian/Greek immigrants and their girl babies had pierced ears.
Children with pierced ears was not a mainstream Australian thing then - that came with later generations.
Lots of girls had pierced ears by the time my daughter was a child - from memory she was 8 when we did it.
Grand daughter just had it done recently - she is 7.