I think that’s the problem, also.
I’m a convert, and didn’t learn about the Friday penance (outside of Lent) until I started googling other things Catholic on the internet.
I’ve met plenty of good, devout Catholics who are/were as surprised as I was that there’s a Friday penance. It’s pretty much glossed over in the Catechism (only one very small blurb that specifies “Lent and each Friday in memory of the death of the Lord” CCC 1438); I’ve never seen it mentioned in a Church bulletin (not even my TLM bulletin); and I’ve never seen a reminder from the Bishops.
Most Catholics that I know, even the semi-practicing ones, generally follow the Friday penance during Lent and on Ash Wednesday.
I think that past 40 or so years have been very poor when it comes to catechesis. But I think we all agree about that.