Manufacturers test their products under conditions that overstate real-world performance? Shit, my faith in capitalism is shattered!

I also overstate runtime when I am using my reel mower.

I just assume that about any battery powered product. Any claims are achieved in unrealistic perfect conditions, so you know the real number will be 30-40% lower. Even Apple does it.

There's simply no standard for testing. They can basically apply whatever "load" they want to calculate the runtime.