Look, I don’t doubt there are people who are always there for every minyan.
Firstly, they obviously have access to a mincha at work or school.
Secondly, their day is probably not very long.
My day is 6:45 to usually 8:00. I daven shachris at shul, and there is sometimes a mincha in my building. I am not going back out for maariv at 10. I am going to sleep.
My situation is, I believe, more typical. Take a poll, ask guys who are working at real jobs (not 9-5). I just don’t buy it.