Alexander,
In the case of the used vs. burned CD, it's really quite simple. A used CD sitting in a re-sale store was bought by someone at one time (unless it's a promo copy). So the artist was paid at least once. When you burn a copy for someone, the artist is not paid at all. Like Aggie said, you are creating another copy, which you do not have the right to do (unless it is for your own personal use).
In other words:
Two used copies = artist paid twice at some point in the chain
One used copy & one burn = artist paid only once for the used copy at some point in the chain
Regardless of all this, considering how ridiculously small the market is for jazz, that anyone would burn copies of discs for their friends and deprive hard-working musicians of income, is something that's beyond me. Yes, I have bought used CDs (rarely and usually only on ebay for out of print stuff) but I don't burn things for people.
This statement is quite telling: "My perspective is that of the music consumer. And as a consumer, who doesn't see ANY negative effects of either buying used or making burns..."
Of course you don't. In the case of burns, you're getting something for nothing. I'm sure the kids that stole the digital camera out of my car a few months ago don't see any negative effects of stealing people's stuff. Does that make it right?
I'm not preaching, just asking.