Here is my theory: Most married males, over time, begin to daven more often. This often occurs as they are raising kids and sending them off to school, and recognize that they should be some form of a role model if they want their kids to get up for minyan in yeshiva.
Consequently, girls grow up in a home where they see their dad davening (him having already evolved), and assume this is the norm. Hence, they expect this as a bare minimum from potential spouses, and are shocked when their husbands in their 20s/30s don't go to minyan.
However, my experience is that davening penetration in the 20s/30s group is quite low, even among people who are 'good' (for lack of a better term) people.