I've got an obligation to maximize profits too: an obligation to support my family. But I don't have the resources Google does to set up complex income shifting tax avoidance schemes, and for that I'm heavily penalized by paying a much larger share of my income in taxes than a company like Google does.
If these big companies want to have the rights and privileges that citizens do (treated as legal entities, freedom of speech through political contributions, etc) then they should have to play by the same rules and with the same encumbrances.
But individuals do take advantage of tax loopholes. What you are talking about is that entities with more money have more options on how to minimise the amount they give to the government.
If these big companies want to have the rights and privileges that citizens do (treated as legal entities, freedom of speech through political contributions, etc) then they should have to play by the same rules and with the same encumbrances.