In response to David, as a second year corps member it really bothers me when people who themselves have not experienced the program comment on its lack of support. Obviously I cannot speak to anyone else's TFA experience, but personally, I have never found the support lacking. During my extremely difficult first year of teaching I had my TFA mentor (or program director as we callt hem) in my classroom once a week, every week, for three months. She was directly involved in reading through my plans and giving me real-time feedback. When I had issues with my school administration, she backed me and even spoke with my principal on my behalf.
Compare this to the first year teachers from a more traditional teaching program who had no mentors, no intervention and none of the resource help that TFA provides. Ask any teacher and they will tell you that making copies is essential. When your schools copiers break down, TFA offers you unlimited free copying at the office. Not true for traditional teaching programs.
People who have difficulty getting support from TFA are usually the people who don't ask for it. This year I'm having an extremely successful year so naturally I see far less of my mentor, but I know she's there to help me if I need it.
Secondly, what study did you read? Current figures show that nearly 2/3 of TFA alumni stay involved with teaching- either in the classroom, in school administration or in school leadership.
Lastly, to address your question, what's better young teachers who care and work themselves to the bone but do revolve or a system where tenured veteran teachers collect their paychecks but refuse to stay past school hours? Do we want to continue with an education system like the one in Chicago where the average ACT score of a teacher is 19, too low for any of them to meet college readiness standards?