Is Indian food more expensive to prepare than Chinese food?
Near as I can tell, it's probably the local economics. It seems to me that the cost is different per "component" but would probably balance out in the end.

Chinese food, generally speaking, relies more on fresh vegetables (carrots, peas, bean-sprouts, broccoli etc.) and meat. This means that the storage costs and spoilage costs are higher relative to Indian food, which is higher in legumes and beans that are much easier and cheaper to store, and last forever when dry.

On the other hand, Chinese is generally quicker to prepare (think stir fry, though not only), which means less time on the fire, and less man-power used. Indian food usually requires more cooking time, which may mean that the restaurant has a larger capital outlay for stove space.

Aside from that, in my experience at least, Indian is usually a register above Chinese for "comparable" places. The Indian equivalent of a Chinese place serving simple rice and 10-12 stir-fry dishes would be a simple Thali bar, but there aren't many of those, as us Westerners like to order several different meat/vegetable main dishes at a time, as opposed to a set menu.

Anyway, note that I haven't done any proper costing of these type of food preparation.