they don't make them reliable. They're not going to sell a $30 cardboard bicycle with Dura-Ace stuff on it.
You have to make them reliable,beside most wal-mart bikes frames are way to small and are for kids.
On my 1 year old trek I had to replace the rear wheel(I wore the hub out) and relaced it with a new coaster brake hub and one of my old wal mart bike spokes and rim and its fine now.the hub only costed me about $20.00,a new wheel would have costed me $50.00.