Theft is always a problem, regardless of your employment status. Bernard Madoff wasn't exactly on Food Stamps when he caused many to lose their life savings and investments.
If you think that someone may resort to stealing objects to support their families in times of crisis, you're manifestly correct. However, I may point out that it's not only people in the lower classes who are committing robberies. As has been pointed out, embezzlement is very common even in the higher classes.
Robbers are either desperate or greedy. If you asked me, I would say that greed usually has more bearing on someone's desire to commit this type of crime than class.