“Most ex Catholics” think they have a choice. Whoever is baptized as Catholic will be judged as Catholic. It’s not like divorce and annulment based on verifiable inabilities.
Not going to mass on Sunday for a Catholic is actually a mortal sin. Always was
https://www.ewtn.com/expert/answers/sunday_mass.htm
I am not denying anything you said. I an only analyzing the data I have read. Pew and the center for religious studies did a comprehensive study on religion and secularism in 2016. Interesting read.
Though there is nothing mandating attendance at church. Just more rules made up by Roman Catholicism to control their membership.