That would simply be the Market at work.
If wages were too low, people wouldn’t work for them. But they do, so that PROVES the wages are reasonable. Sure, they could raise the wages, but why should they? The workers are still working, still willing to show up on time, and it keeps costs lower. Were they to raise wages, they would have to FIRE more workers (that’s what happens when you raise wages, this is empirical fact), and the price of burgers would go up. Then people wouldn’t buy them, then McDonald’s would once again FIRE more workers because of a reduced demand, and you’d be back in the same boat, just with less people working. (stole that paragraph from http://www.chinadaily.com.cn/opinion/2007-03/23/content_835150.htm cause I liked it..short and sweet)
Still the POWER LINES in the story above are : FEWER TEENAGERS ARE WORKING PERIOD!!! DING DING DING DING!