I found your post whist trying to find an answer to the same problem. Both Illustrator and Photoshop have nice easy transparency grids so you can visualise transparent areas. Indesign uses the printed page metaphor so by default the page is paper white.

The solution is quite easy, just go to the colour swatches and edit the ‘Paper’ swatch to a visible colour. It doesn’t matter what it is as when you export to PDF eg. it won’t show (because in feet it’s transparent) this also works for knocking out text etc.