Bluetree, the fact is that some of us have a hard time learning or doing this. It's not that we "won't." I can do every part of the tube/tire thing, but I cannot get the rear wheel back on. I know what gear to put the derailleur in before taking it off, but by the time I do that and lay the bike down, I am lucky if the chain isn't totally disengaged from everything. If I manage to not do that, it is almost impossible for me to hold the rear end of the bike up, position the chain over the ring, pull the derailleur back, and get the bike into the drop outs at the same time. It's like I need 3 hands. I have actually pulled my back out, twice, from trying to do this. And my bike weighs less than 15 pounds. I am totally uncoordinated, have really bad fine motor and spatial skills, and while I want to be independent, if there's someone else there to do this, at this point, it's fine with me. Of course, I have only had 3 flats in 10 years. Two were at home, thankfully. My DH can change a flat in like 2 minutes, and I am not exaggerating. He can also do it without tools, if need be. So, believe me, it's extremely frustrating to not be able to do this. And when I've tried to practice at home, I just end up with my bike in pieces and me crying, pretty much. Frankly, I don't want to break my bike by bending something while "practicing." I am not kidding when I say that sometimes, I can barely zip a zipper. For me to be riding 3,000 miles a year is a miracle in itself.
I hope this gives you a perspective on why some of us have trouble.