Hi Sam,
You make some observations, i believe valid... there don't appear to be any clear channels where "angels" are listed. There are a number of groups like Sydney Angels, but unfortunately, their reputation (or track record) are not something the ecosystem can point to with pride.
However, there are plenty of angels, many of them are at events, for example, people like Andrey Shirben, Terry Hilsberg, Pete Cooper and the likes can be found at various events while others like Chris Gabriel won't be seen at many events at all, however, they (and many others) are very real angel investors, probably with over a dozen investments each under just in the past few years alone.
I have personally invested in about 6 companies (albeit small amounts; not including the 8 companies that come via pushstart as i was an investor in the round), and get sent over a dozen pitches a week - the others i have named probably get twice or three times what i get (they are much more professional investors), so you'll appreciate that they don't have time to reply to every pitch they receive, they filter based on the recommendation it's come via, the quality of the application and of course, their preferences for particular types of businesses. I doubt very much if the US (or anywhere else) is different. If you tried to cold call/email Brad Feld or Dave McClure with a pitch that is less than brilliant (and sometimes even then), i suspect, you won't get a response - so why should anyone expect anything different from any other investor (everyone only has 24 hours in a day, there are no exceptions!).
As for expecting responses to questions, the community will absolutely step up, but after the honeymoon period, if it "appears" someone is asking for something without having made "any effort" themselves, people don't like to be treated as other people's butlers. All i'm saying is that if you give more context when asking something (aka, if you had mentioned that you had been to events in 2013/14, named a few of them, given your experience - not asking for pages, just a sentence or two), then you are much more likely to get people making an effort to respond with more effort and thought. You might be new to this list, but i suspect you are not new to "mailing lists" in general, and will notice that pattern everywhere.
Anyway, looks like you must have been trying to start some things here in Australia in the years gone, it's always good to have entrepreneurs with a variety of experiences doing exciting things, hope you come back and give it another shot, the ecosystem gets more vibrant by the day.
kind regards,
simran.