Well, he certainly doesn't have to. There's no worldly force automatically granting you a bonus as well. But on the other hand there's no worldly force keeping you at your job either.

But if you feel you can demand complete fairness, then everybody else on this planet can too so why don't you give a "bonus" to someone homeless who doesn't have anything – even tough you didn't get one from your boss? That is true morale because it requires strength to exclude yourself from the equation.