Catering businesses are a luxury service. Since the rift between the haves and have-nots is growing, there may not be more people with money to spend, but the people with money have more of it. Therefore though it may seem counterintuitive, demand for luxuries is actually growing. The people that have money to spend will spend it on increasingly luxurious items. This means having parties and needing caterers. Perhaps we should call it the Gatsby effect!
Another factor is that the economy seems to be getting better, and as people have a little more money they scramble to regain what they have lost. This means throwing parties, having weddings, and hiring caterers.
The specific reason for catering being in demand would vary depending on where you are living. However, the general reasons for an increase in the demand for catering are somewhat similar in all places.
First, the demand for catering is likely to go up as people become wealthier. As they do, they are able to afford more in the way of luxuries. Catering is surely a luxury and therefore increased consumer income would lead to increased demand for it.
Second, if people's lives are becoming busier, catering might be more necessary to their lives. If they are too busy working, then they might not be able to do as much cooking for themselves. This may be especially true as women enter the workforce.
So two major factors that would increase the demand for catering would be higher incomes (so more people can afford it) and busier lives (so that more people need it).