Ah you sweet child. Go to any legit second hand store and ask for the original receipt for the item. Nope. A charger may well have been changed or another similar one given after all it’s only USBC.

There are a plethora of reasons why a legitimate seller may have a non standard charger and when I sell an old phone or a laptop on a market place there is an expectation the item isn’t stolen. It’s called good faith in contract law and why you can’t be guilty of handling stolen goods if you have no knowledge or expectation of it being stolen. For example if you buy it in a pub with a dog and 2 kilos of meat all for £50, then there is a reasonable expectation it is stolen, but buying from a second hand electronics store or eBay, there is an expectation it is not stolen.

As for someone else’s login, well if you wipe the drive or factory restore it, it no longer has anything on it and can have no such identifiers. This is why I stated that Steam can and I believe should do more to make the device lock down, but they have no incentive as it costs them money to implement and manage but with little to gain for them.