When I was a kid, there were two places people bought bikes: the Schwinn store and Sears. Most bikes had one speed or three speeds and coaster brakes. Sears, at that time, took quality seriously, so many of their bikes were almost as nice as a Schwinn, and cost a third less.
The impact of Wal-Mart has been to force stores to sell the very cheapest stuff in the cheapest way. So, today, discount stores are full of bikes with 21 speeds and dual suspension. Poorly assembled. Unsafe to ride. Take them to a GOOD bike shop to replace broken parts and it turns out many of the parts are not standard parts.
Wal-Mart bikes, if assembled by a really good, experienced mechanic, would last about three months in the hands of a typical eight year old boy. And, that is what they are designed to do.
If that same eight year old boy is given a $200 single speed BMX bike from a good bike shop, he will be able to ride it for five years, then give to a younger brother who will ride it for five more years. On a "per mile" basis, a $200 bike shop bike costs about ten percent of the price of a $75 Wal-Mart bike.
If Wal-Mart was run by ethical, honest people, it would sell one speed bikes with coaster brakes. The factory could fully assemble and test the bike, and ship it to Wal-Mart with the front wheel off. Such a bike could be sold for $75 and be a safe, reliable, and long lasting bike.
The junk Wal-Mart sells is proof that they think the typical American consumer is a half-wit. A clue to how smart they think customer are: all Wal-Mart bikes with 26 inch tires are exactly the same size: Wal-Mart calls it "size 26" - as if some adults are NOT five foot one, and some are NOT six foot four.