It seems like the point is that we’d be naive to expect a corporation, presumably governed by rational actors working to maximize profits, to pay more taxes than the minimum.
Is your position that corporations don't have an unjust advantage, or that the unjust advantage is okay and people shouldn't complain about it?
Notice that I haven't made a claim that corporations should be treated as individuals, or that corporations do or don't have an unjust advantage, or that having an unjust advantage is okay.