You do call elk in but the only elk you will call in is a bull.
I have called in lone cows, or a cow and calf, on numerous occasions.
Cows are pushed by bulls when they are in the rut.
In my experience, the lead cow does just that, leads.
The bull keeps them together, and tries to get more, but usually is in the rear of herd, or circling.

I guess it just shows that anything can happen

We all have different experiences.