Consider a master page as a background or background picture. The point of it is to have similar elements on a certain number of pages, like headers, footers etc. You cannot place an element on a master page and change it on normal pages. It goes against the sole concept of master pages.
So, for example, you can put guides or other objects on a master page which will appear on all pages to which that master page is applied and which will help you have uniform-looking layout, but you'll have to create text frames and image frames on normal pages.