how does the board show they are motivated by greed and not by the welfare of the children for which they provide?

At nine, Oliver is too old to stay in the orphanage, so Mr. Bumble comes to get him and take him back to the workhouse where he was born. There, Oliver is taken before the board, who think he is a fool and decide that he will begin to pick oakum so he can learn a useful trade. (The board has recently instituted a program whereby they will slowly starve those in the workhouse so that there won't be so many of them.)