She works full-time representing poor clients who cannot afford to pay for a lawyer. But she is paid, say, $50,000 per year. As another commenter pointed out, the fact that she is paid for her work means that -- if pro bono work must be done solely for the public good -- she is doing no pro bono work at all. Yet she is spending her entire working life representing poor people, and makes one tenth the income of Lawyer A.