The 70's were the richest period in American filmmaking history. The films of the time reflected the cultural upheaval going on. While Schrader was certainly part of all this, his work stood apart from everyone else's, because of his stern sense of morality -- even though his work was as rich and complex as anyone else's, Taxi Driver, Hardcore and American Gigolo upheld traditional values in the end.
I guess that, particularly in the case of
Taxi Driver, I just don't see that.
My strongest reaction here is to your comparison of Eastwood and Schrader, asserting that they are somehow from the same school. So the proper comparison is between Eastwood's Dirty Harry and Travis Bickle.
To begin with, I clearly see the seventies as less "hedonistic" than you do- and its cultural "upheavals" as having a very positive side- and Eastwood's films as much more reactionary. But to me, the differences between
Dirty Harry and
Taxi Driver is obvious: The former is a celebration of vigilantism and a complete rejection of contemporary society and its shifting mores (which it knee-jerk equates with crime and terror). It is so small-minded and black-and-white in its "morality" as to be stupid. The latter, on the other hand, sees Bickle's inability to cope as triggered by the outside world, perhaps, but just as reflective of something in him. The world may be turbulent, but his reaction to it is at times both pathologic and misdirected. Travis Bickle is emblematic of a much more complex, humane, and empathetic vision of the world and society than Dirty Harry is.
To the degree that
American Gigolo is a precursor to those atrocious, sleazy-moralistic films of the eighties I mentioned before, it is a failure (which it is considerd to be by many critics). I don't believe Schrader's goal has ever been moralism, at least not in any simplistic way; his espoused goal for
American Gigolo was to be a latter-day
Pickpocket, mapping a spiritual journey and exploring human conscience.
The "sliver of redemption" you speak of in
Taxi Driver is, to me, not the result of a moralistic impulse, but of a humane one. The girl is saved at great psychological/spiritual cost (via violence) to both herself and Bickle. There is little triumph in the violence; it is excruciating. On the other hand, there are no such "slivers of redemption" in
Dirty Harry. It's all "get the bad guys." We're meant to cheer when the "evil" people are blown away. Which is fine and definitely part of a movie tradition, but the particular, vehement tone of that series of films, where the violence is its own vengeful reward and there is a definite sadistic pleasure in it, is what makes them, in my opinion, the dregs of its era.
The main difference I see between
Dirty Harry and Schrader: Dirty Harry looks at the then-contemporary world and says, "If only everything could just go back to the way it was before. Everything was fine before. Nothing needed to change. These changes are wholly destructive, and somebody has to stop them."
Schrader says, "There is confusion and turbulence in the world. How does this affect us on a personal and spiritual level? What can we do to help ourselves and others get through it? Is there a light at the end of the tunnel?" He doesn't dismiss the changes in some reactionary way; he sees them as troubling and disruptive, which of course they are, but he's simultaneously much more pragmatic and much more idealistic than the
Dirty Harry stuff would ever think to come close to.
To summarize my opinions on this:
Dirty Harry = Small-minded, simplistic, reactionary, pandering, and not a little dumb. Schrader = An important, hardly judgmental (or "moralistic") chronicler of the inner effects of a confusing outside world.