I think the main problem is lack of information. In most places, bike shops have lack of presence and thus, cannot relay the information on bikes. Personally, I only knew of one bike shop were I used to live four years ago (Silver spring, MD), though I was only 14 at that time and wasn't really into cycling as I am now. Where I live now (Athens, OH), the bike shops have a bigger presence (smaller town by a huge margin).

When I was growing up, my parents were very poor. A bike every 2 years was hard on my parents (though it did get handed down to my brother). I remember that I was always excited to get a new bike as I had out grown my previous one and excited for the new 10, 12, 18, etc speed bikes, and the 20, 24, 26" tires. I think a lot of parents figure, the bike is going to be outgrown in a year or two, and the kids throw the bikes around after they get off it anyway.

Now I walk through walmart looking at how bad the bikes are and how I could buy any one of them with just one pedal off my bike.