Ill-fitting Shoes

Why do people wear ill-fitting shoes? Is it that difficult to find pairs that fit your feet? Or to at least find inserts or padding so that your feet aren't slipping, or that when I'm walking behind you in the mall make it so that I don't notice that your shoes are clacking too much and that you are limping in pain yet you still wear those cage heels that are a full size too big for you? I see the gap; were they worth it?