User blog comment:Metal Mario875/Mario's Feats Compilation/@comment-32286613-20170614122816/@comment-26374068-20170614124334

Actually, this is explained through the same logic as the neutron stars and castles in SMW, plus moons, planets and galaxies in SMG.

The Marioverse scales things down to fit graphical and technical limitations. Of course they cannot have Mario being chased by a star drawn to scale... he'd dwarf the screen, encompassing everything. He'd be in every level, too. They size him down to fit on screen.