Being a good steward means making responsible choices as to how to use resources. Just writing a check to big government or big church thwarts this tesponsibility and leaves us as passive rather than active citizens in church and polis. Evangelicals are far better stewards of financial resources primarily because their institutions remain financially decentralized. Just because we have a bishop, it does not mean that the diocesan financial resources have to be concentrated in him. It seems that large chanceries and the USCCB have wasted hundreds of millions of lay dollars on bureaucracy alone. As spending at the diocesan level has gone up, "mission effectiveness" has gone down. At an institutional level, the Church is failing miserably in its role as pastor, teacher, and evangelizer. Is there a connection? I think so. Renewal in the Church today has largely come from independent initiatives of the laity as well as the movements, who were galvanized by the late Holy Father (mirroring other renewal movements within Catholicism - Gregory I, Cluny, Franciscan, Trent).
But once again, the real problem is that bishops should not be making particular judgments about certain pieces of legislation, especially involving economic matters. They should elucidate the principles clearly, consistently, forthrightly, (subsidiarity, solidarity, the dignity of work, preferential option for the poor) and not feel afraid to condemn certain things that are clearly violative of human dignity. They could even lead rallies on the capitol steps where they protest grave injustices. However, they should not have organized bureaucracies where particular policy initiatives are pushed.
Jason would even extend this to abortion, and there I hesitate a bit; I think abortion is such a direct violation of the natural law, and violates human dignity in the most extreme form - murder - that it justifies direct political involvement. Even so, at this point perhaps the best place for the Church to start is at the beginning: showing Catholic legislators what their Church teaches. What a concept!