Store brand tshirts from places like C&A are often entirely plain, meanwhile expensive brands like Gucci are all about plastering their logo everywhere. I'd be surprised if Gucci shirts actually had lower production costs than C&A shirts.
Even brands like gucci and their line up, their entry level will have bigger brand logos, because they know people who buy entry level gucci are people who want to show the world they have gucci. Real rich people will buy something more cleaner looking.