In a car when a major part is replaced or upgraded, and then it is sold, the seller shows receipts
Yes well cars have many components which cost thousands of dollars and are mechanical with an expectation of lasting years, so there is a meaningful depreciation. Also a car has many systems and is much more complicated than a laptop.
Then you have laptops which pretty much have the SSD and Battery. Every other module is not a single part but many electrical parts and ICs. Monitoring the hours or usage activity is probably not the right thing to begin with for 99% of the parts in a laptop.
Everything degrades so slowly that wear is not much a consideration - a LCD with 5000 hours on can even have a slightly lower failure rate than a brand new one; a depreciation based on usage doesn't really work, because with electronic components it's not strongly related to how much longer the part will last.
Buyers' main concern should be do you have components with failures, when was the manufacture (How old are those caps and ICs), and have those failures been fully corrected with a stable resolution and not a band-aid. And do you have a latent defect that is going to cause a frustrating experience such as random system crashes which has not been tracked down to a specific component. (EXAMPLE: Is the reason this laptop is on the used market is because the owner got frustrated with random glitches and therefore discarded it?)
This is why extensive hardware monitoring testing is suggested. I don't mean casual tests. Run those CPU and Memory at 100% for 72 hours each, sure. But having that device log whether it's run Error-free under normal use over a long period of time should be a huge part, and just as important as some short term stress test.
99% of a laptop's parts are expected to last 5x as long as you would ever use the device. That CPU's lifetime is determined by the date of manufacture not its amount of usage. That LCD that's good for 80,000 hours before it degrades to half amounts to about 30+ years of usage. You could expect a bunch of those 10-cent capacitors on board to die out and numerous other failures of individual electrical components before the largest parts itself degrades from actual use, And there's no way to directly account for the usage and status on all those individual PCB elements.