Because, why would they have to? They're not even supposed to.
Like the plot of a certain popular sci-fi movie, but without the part where it all makes sense.
We're talking things like: Why Not?, It Doesn't Matter, and Who Knows.
Visit our sister site, Another Random Thing for more things that don't make sense.
Disclaimer: Our lawyers have advised us to mention that none of this is actually true. But you probably knew that already.