No, they don't. I just asked a room of seven guys if they cared if the NHL season was cancelled. Two of them said, "What's the NHL?". Five of them said they could careless as they had never seen a hockey game. Two of them said it didn't matter and they knew what the NHL was. One of them said he was fan and that he cared but said it was a necessary evil for the Coyotes to survive (I didn't realize one of my co-workers was a hockey fan).
What may be thought of common knowledge to you is not common knowledge to someone else.
You were brought up watching the game and being exposed to the NHL, likely live an area where the game is king and followed like a religion, so it is hard for you to fathom that someone does not know what the NHL is. But there are parts of the United States who have never been expsoed to hockey, don't know about hockey, and don't care about hockey. The NHL is a term they would never know, especially if they are not a sports junkie or from a region where a franchise is located.