I was pondering this earlier and couldn't find a quick answer.
If I go to a restaurant in my neck of the woods (Alberta, Canada) and order a "Steak Sandwich" on a menu it invariably looks like the following:
A toasted piece of french bread or bun with an uncut piece of grilled striploin on top. It may or may not include sauteed onions and mushrooms and it never has the top piece of bread. Kind of like a tuna melt.
When I google steak sandwich all I get is the Philly variety. In Alberta if you want a "philly cheesteak" you have to find a place that lists it as exactly that.
So I'm wondering, is this a regional thing?