Further to this, corporations are (composed of) people[1]. Apple is paying out dividends this quarter and the shareholders will pay taxes on those dividends. Corporate taxes are an expense to a company that leaves them less money to spend on other expenses, including R&D, hiring, lowering prices, and competing for labor.

[1] The “composed of” was obviously what Romney meant in the 2012 campaign, not an obscure argument about corporate personhood.