Can an image placeholder be made transparent in Impress?

In Powerpoint, an image placeholder that does not contain an image appears as transparent, aside from the small text ‘INSERT PHOTO HERE’.

In Impress, the entire image placeholder appears as an opaque image of some mountains. Can the image placeholder in Impress be made to be transparent?

It is confusing because some elements, like text, are visible over the placeholder image, while other elements like a background image are not visible. I feel that it should either cover all elements, or no elements. Why does it allow the text to be visible, but not the background image?