You are comparing an industry where a single model run is typically on the order of 20-80,000 units per year to an industry where a single model may put out a few hundred units per year. You can't expect the same level of statistical relaibility numbers to be available.
It's also not practical for the manufacturers to apply the same level of quality control without costs spiraling out of control.
Reality is the vast majority of manufacturers use the exact same hardware, frames, axels, appliances etc... There are likely some differences in the reliability of the actual assembly but after that they are all very similar.
Of course the high end manufacturers put out even smaller numbers than the low/mid range so it's even harder to create mass production efficencies and quality. Thier saving grace is they can afford to have people back check work and just cover warranty issues without a fight.
Don't expect there to ever be a reliability guide like you will find with cars.