Why do Corporations Give to Democrats and Republicans?

Corporations care about one thing, gaming the rules in the laws so as to be most favorable to them.
Small businesses just compete within the rules.
Corporations are big enough to realize, "They can write the rules."

But how do corporations make sure that the senator with the pen is listening to them?
They give them money!
But surely, Andrew, you ask, they couldn't possibly give money to all of the candidates?
Well, As Barack Obama sort of said, "Yes They Can!

Corporations can cover all their bases if they give to Democrats and Republicans. As long as they can keep any other candidates out of serious contention, they know that either a D or an R will come after the congressman's name.

So they give to both.
Cause it works.

One of the oldest reporting rules seems to be one of the hardest for us to get a grip on...
"Follow the Money."

Corporations' money goes to making sure that either the Democrat or the Republican wins. That legislator then write laws so that whether the coin lands heads, or tails.
They win.

Third party candidates have a hard time in National Elections because of this dynamic. But local races are a whole different story.
But that's for another day.