I agree, the standard in the US is for proactive service.

IMO the near term solution in these situations is to ask.
Flag down (as you did). Ring the call button to ask for service if you are in J. I've done this when I have to. While they are varying degrees of delight in responding to the call button, I have never been outright refused or told not to use it. It sometimes also sets off a parade of requests from the cabin.

Yes - it shouldn't be that way. But when you are already on the flight, not much else you can do and you can still make it a better experience by asking for it.