'm not sure I completely agree :) Fortunately (or unfortunately) the transmission line acts as a impedance transformer. Given the length of the transmission line, impedance "shown" on to the TX might be the same as antenna's impedance, or quite different (depends on transmission line length and it's impedance).
Like wise, what TX "presents" to the t-line is not what will be presented to antenna (the same principle where t-line transforms impedance).
I do NOT known if this transformation done by the t-line is reciprocal: let's take a simple example. Take antenna tuner out of picture, so you have TX(50), t-line(100), and antenna (25). By carefully selecting t-line's length, you can transform antenna's 25 to match TX's 50. I think (!?!) that at the same time, on the antenna side, using the same t-line magic, TX's 50 will be now "presented" to antenna as 25!
If this is true (is it?), you can expend to any length of the t-line by adding antenna tuner - whatever t-line presents to TX side (let's call that Zx) will be matched to 50, and like wise, TX side will appear to t-line as Zx, and t-line will transform that to 25 on the antenna side.
If all this holds water, if TX sees SWR as 1:1, that means that SWR on the antenna side is the same!
Two (hand picked) examples of reciprocity:
1) lambda/4 t-line transforms short (0 ohm) to open (>>0). Wise versa is the case as well: >>0 on one side transforms to 0 on the other
2) lambda /12 t-line does magic Z1*Z2=sqrt(Zt) (multiplied impedances from each side are square root of t-line's impedance
If, in generic case (any t-line length/impedance) the following holds true Z1=k*Z2 and Z2=1/k*Z1 ("k" is impedance transformation "factor" that t-line does), it appears that good SWR on one side is good SWR on the other as well, right?
Now, you make an interesting point, if all this magic is happening by "bouncing" waves back and forth, cost of doing it with real t-line with losses might be significant - wave bouncing back and forth will lose some of it's energy in the t-line, and seeing SWR meter showing 1:1 on the either side will NOT indicate that such losses are present. Antenna tuner will make t-line/antenna appear "friendly" to TX, but will not deliver all the power to ether
