One answer to that is laziness in some cases. What is easier? Getting something pre-made or taking the time to actually make something healthy for yourself. Oatmeal is rather cheap and not bad for you.
They stock it at Wegmans
Some apples
And honey instead of using processed sugar if you want to sweeten you oatmeal.
Or you can go to McDonalds for Bacon Egg and Cheese Bagel.