A text shape has a behavior that is the same as a special configured compound shape. Notice that the rectangle is selected when you type your text this clearly shows that your text shape is really a compound shape. In fact, the default text style is surrounded by a oblong which has no fill color, no shadows and no line strokes.
This also means that it is possible to start with a text shape, and then convert this into a compound shape. This is not something you normally would do, but working through the steps teaches you the how's and why's of the text shape.