They are really competing in entirely different environments. Retailers tend to employ younger workers who are more interested in income than benefits, so they don't demand strong retirement plans. And turnover often is high. Companies' profitability also plays a role. But profit margins don't tell the full story.
Experts credit a strong union presence, which tends to raise the level of benefits for all workers.
Another way to look at the issue is profits per employee, says Bob Dankmyer, vice president of benefits for Marriott International. It also has a pension. If you go past that, you might be able to sustain it for a little bit, but eventually it leads to bankruptcy.