All audiences, whether viewing a movie, reading a book, watching an advertisement, or listening in a classroom, expect the same things:
To learn something
To be entertained
To feel that whoever is delivering the message knows what he/she/they is/are talking about
To feel their time is not being wasted
To clearly receive the information they thought they were going to receive
In writing, this means that we all agree that we want something that’s “clean” (in terms of formatting, like the font size doesn’t suddenly change sizes), easy to read (in terms of grammar, punctuation, and spelling), organized well, and making a clear and an interesting/funny/useful point.
Different audiences will warm to different styles. Some audiences will expect to see evidence of detailed and careful research, such as a supervisor.
However, not all audiences like the same things. Those aspects of us that make us different are demographics, things like:
Where we’re from (part of the country and urban/rural)
This is why there are so many different magazines in the world. Sure, anyone can pick up any magazine and read it, but publishers of magazines always have a target audience in mind. You can think of a variety of magazines and imagine what their target audiences might be. The audience for Field and Stream is different than the audience for Cosmopolitan and much different than Dollhouse Miniatures Magazine. This isn't an accident.