I'm an engineer and I do the reliability and maintainability studies that are used to determine the warranty and maintenance schedule on a product (being vague on purpose). I go through everything that can break, figure out how it can break, and then figure out when it will break on average.

A long warranty means less than the OP thinks, depending on the product. The company takes my numbers and excludes key parts from the warranty. So for example, a refrigerator compressor is extremely reliable and will be the basis for a 15 year warranty but even the cheapest is likely to last well over 15 years. They'll offset this by using cheap plastic for the shelves that are excluded from the warranty so the difference between the cheap fridge and the expensive fridge is not the quality but the cosmetics and both will make more profit selling replacement shelves than they did on the entire fridge.