Why is this considered wrong

I am new to japanese, but from what I know Shinbun means newspaper and hon means book. However in my textbook I always notice that they will show a picture of a man or women reading a newspaper and call it a book for example. Onna no hitotachi wa hon o yonde imasu. The picture however depicts a group of women readin the newspaper. Why is this.

because your textbook is strange.

Maybe to the editor, who happened to have bad eyes, the newspaper looked like a book. It could be something as simple as that! There could be any number of reasons why, but all of them would be circumstantial and not related to the Japanese.

Shinbun is newspaper and hon is book.