If you didn't know this, and are a freak about expiration dates...
They are completely made up by the company that produces the product. As someone who manufactures dairy and food products, we make our dates up.
We take in information from science and data. We minimize risk (have to be sure there is no chance of a lawsuit from people getting sick).
But the key factor is taste and freshness. So, if my food product (lets say protein balls) starts to taste not as good after 2 weeks, we will probably put that as the date. We don't want people eating our product unless it is of optimal flavor and taste.
So, we make sure that no products can cause sickness within the date. Then we make sure that taste/flavor/texture make the product still good, and then we push as far out within those realms so consumers will purchase and not waste it.
Wasted food makes them upset, costs them money, society more money, and nobody wants to see their product trashed.
Can you eat it after the date? 99% yes, depending on the product. It may taste a little less, but it most likely won't get you sick.
We can change the date at any time, for any reason.
It is all up to the manufacturers.