Main camera position for television

As someone who works in television production, I was amazed watching the Fire game last night at the number of times we'd see some random person's head at the bottom of the screen, walking directly in front of the main camera shot.

It's beyond comprehension to me that they don't either block off whatever walkway is right in the way of the camera, or raise the camera position on some sort of platform so that it doesn't happen.

I've never been in the venue before to see the actual setup, but it's crazy to me that they just let people walk right across the shot like that.