If you have a $100 in your pocket and thats it...then Wal-Mart is the only place to buy the bike. But if you want a bike that last five years....then I'd spend the $200 and go elsewhere.
I'm only trying to suggest parents consider an alternative that involves a bicycle shop as opposed to the Mega-Lo Mart.
The safety of the bike is largely a matter of who assembled it. Your odds are much better at a bike shop of having a qualified person assembling it. I'm sure there are a few fine bike assemblers at WalMart or wherever, but they aren't the norm.
Many who ride hold this view. Just sharing it for others to consider, especially parents.