Hmm, having handled some of these assignments, I would say it's not done to increase billing hours. People keep their traps shut for two reasons: deeply hierarchical Indian org structures that don't tolerate opinion, and wanting to reduce friction as much as possible. The times we have pushed back we have been faced with "well, what do you know?" When that happens, the first guy to get slammed is the guy who asked questions. Rinse and repeat over a couple of projects and you get teams that will unquestioningly build you a handcart with a rocket engine.
Wanted to add, for every dollar an Indian firm makes, the average developer gets probably around 8-10 cents or less. When you are at a subsistence level like that, it's difficult to ask questions. You focus on the insecurity instead.