Why is work = giving-presentations?

Have you noticed that almost any ad/movie about a guy or gal doing work has something to do with giving-presentations? And usually the presentation has a chart (line-graph going up or bar chart growing taller) and then everybody in the room listening to the presentation is wearing full 3 piece suit and shining glasses. Each one of these people have a few sheets of papers in front of them. They all have ball-pens; and they are thinking.. After sometime for no reason they all clap and the dude/gal giving the presentation is super-surprised about the adulation.

I know that I work. I know that I work rather good. But I don’t give presentations every single day to a room full of people in suits. Perhaps I am not doing any worthwhile work at all! Because the ads sell stuff to “working people” giving presentations and I don’t. Perhaps they are targeting only the movie characters that do give presentations all the time at work.