Definitely agree with this... it's all training.
my sister and I went to mass every week and sat there without snacks or playing up. I remember counting down hymn, collect, reading, psalm, gospel, hymn, sermon, hymn communion, hymn... and zoning out completely in the boring bits.
Our kids sometimes go to church but expect there to be a colouring table at the back and Sunday school half way through. They have never been trained to sit through something like that for over an hour.
Our kids are otherwise generally better behaved than my sister and I were at home though 