The Devil is in the details.
That's what's at work here. We have the basic premise that songwriters (and performers) have a right to remuneration for their works, but how to collect? How to police the marketplace? That's the sticker. ASCAP, BMI and SESAC are US "artists' collection agencies," and, due to some of their practices and policies, don't do it to the satisfaction of all.
In particular, unpopular musics are not covered well, with folk artists getting damn-all for their work, and pop stars getting the gravy and the pan it's in. And venues that might employ or feature folk artists and folkish songs (i.e., new songs in "folk" style) are leaned on by the operatives of the PROs (Perfroming Rights Organizations) under arcane rules that don't fit them, but are used anyway.
What's needed is more flexibility for and from the PROs, coupled with some realization among the folkies that the music isn't "free," any more than clean water is (for that matter, any more, these days, than clean air is). If I create something musical that others want to use, I expect them to pay for it. If they use it "for free," as in, they don't make money off it, then the payment should be recognition that I created it. Composer's credit. Public acknowledgement. If they make money, I expect some monetary return (above a threshhold level, of course -- it'd be stupid to ask for the 7.1 cents from one performance in a pass-the-hat coffeehouse). If they make lots of money, I expect to pass out from surprise.
I have registered copyrights with the Library of Congress' Copyright Office for some of my songs (I'm behind in this), and it costs $30 ($20 if you do it before July 1) for one or many songs, if you register the whole "thing" as a collection. (All the songs in a collection must be by the same authors, so if you co-write with others, you may have to group 'em by authorship). I can't find the URL, but someone's sure to post it.
The "poor man's copyright" won't hold water (you only have to have a sleight-of-hand magician do one of those "card into a sealed envelope" tricks to put doubt in the jury's minds and poof! there goes your claim.) As for being good to use only once, the use, if it worked, would create the legal record of the claim (you'd use it in court, during litigation, of course), so the thing would only have to work once anyway. But like I said, it's a really weak reed to cling to. Posting on the internet could provide more protection, since it'd be stored on server disks and those are date-stamped, too, and it's much harder to change those dates than on a registered letter.
Enough blather. We need to push for changes in the PROs methods, not throw out the baby with the bathwater.