Great period piece. Why'd they go & spoil it at the end?

Rating: 9/10 (8 May 2012)

Sat down recently & re-watched Once Upon a Time in America, the whole nearly-4-hour epic. I soon found myself thinking what a great film it was & trying to figure out why I'd come away disappointed the first time I saw it years ago. But as the denouement came round, I remembered it was the ending that spoiled it for me.
The movie begins with a 30-ish "Noodles" (Robert de Niro) on the run, hiding out & smoking opium in a Chinese den while gangsters hunt for him in the Chinese theater that fronts it. We fade to a 50-ish Noodles arriving back in NY, where he apparently hasn't set foot in 20 years or so. Then we go into the long flashback that comprises the bulk of the film. We see him as a kid with his gang & witness his first encounter with his soon-to-be best friend, Max, & follow their exploits as they all grow up to become major gangsters during prohibition, Eventually, the rest of the gang gets set up & wiped out, Noodles hides out in the opium den and then discovers the gang's communal money cache has been cleaned out, forcing him to leave town empty-handed.
Then we're back in the present, where the now middle-aged Noodles looks up some surviving acquaintances & eventually catches up with Max (James Woods), who's now (under an assumed name) a pseudo-respectable businessman & politician. He's about to go down for white-collar crimes that have caught up with him tho & he invites Noodles ("the only one I can accept it from") to be the one who kills him. But even tho he now knows Max was the one who ratted out their gang - their lifelong pals - & got them all killed, Noodles declines to shoot him. Unsatisfactory outcome, I'd say, but alright, I reluctantly accept it, that's Noodles' choice & he's a changed man & all. In any case, the movie should have stopped there.
But no. When Noodles leaves Max's mansion & starts to walk away, a large menacing truck starts its engine, turns on its blinding lights & starts slowly following him, making you wonder if he's about to be whacked. Then you see Max outside his gate, the truck passes him & suddenly he's no longer there. When the truck passes Noodles, we see it's a garbage truck & we're given a good long look into the back where two big macerator screws are ripping everything up & shoving it into the container.
This whole long slow sequence is clearly meant to be significant as hell, but I don't get it. Are we supposed to believe Max tossed himself into the truck? Or that somebody was waiting to whack him & toss him in when he so conveniently stepped outside? Or did he just go back inside & this whole truck thing is just a red herring? Or hey, maybe it's pure symbolism, man, don't you get it? Like, he's relegated to the garbage can of history. Uh-huh.
While we're still pondering that, we're gratuitously returned to the opium den where Noodles was hiding out at the beginning of the film. He's the same age he was back then, so evidently we're back to that point in time. What the hell's that all about? What a pointless confused ending for such an otherwise brilliant movie.