In France less than 4% of Catholics go to mass. The rest of Western Europe has similar numbers 4-7%. In Brazil, the country with the largest Catholic population 7%. And of those miniscule percentages, they are mostly old ladies and no men. What country are you talking about? Scarcely anyone LIVES the faith, going to mass means nothing, and no one even does that. The Vatican II religion has made the Catholic faith irrelevant.
You are completely right — I've seen it personally.
I was baptized as an infant, but I can count the number of times on one hand that I've seen either parent at Mass.
It's a very common phenomenon in countries where 70-80% of the population are one religion, because it's not seen as actual religious practice, it's just something cultural. It's something you identify with by default.
I know, for example, my own mother and father. They are the most poorly-catechized people I've ever seen. Couldn't tell you a thing from the Catechism. Never married in the Church. Still identify as Catholic.
Here is an article from Mexico which reads, "90% of Catholics in Mexico don't go to Mass"
If they go to a church, it's probably an Evangelical or Pentecostal church.