In the United States at least, the design of mass-produced furniture if covered under ANSI/BIFMA (Business and Institutional Furniture Manufacturer's Association) X5.5. I don't have a copy of the standard to give you specific values, but in broad strokes the requirements for consumer goods like this (where the consequences of failure are much less than in an airplane or a building) codes focus less on design and calculation and more on testing of a physical sample.
One important aspect for furniture (not unlike airplanes) is that in addition to handling a maximum load, it needs to be able to handle many cycles of loading and unloading. Because of this, the design may well be governed more by the number of cycles the desk needs to be tested to than the maximum weight it needs to support one time.
Another major distinction is that in the US, manufacturers are not required by law to conform to the standard. Unlike airplanes, where the FAA has the authority to require conformance with applicable standards, furniture is not centrally regulated. As a way of controlling quality though, many large purchasers like schools or corporations will require conformance on all products that they buy, causing some manufacturers to develop products that conform. The difference of course is that it is perfectly legal (and common) to sell a desk that has not been tested by the standard.