As a European, that's something I have a hard time understanding. How can it be legal for a corporation to buy politicians? Corporations are not people in any meaningful sense of the word.
They are not buying any more than you are buying a politician by donating to their campaign, putting up a sign with their name on it in your yard or voting for them.
Many people think this is buying, it is simply helping the candidate you agree with the most win the election.