What happens when you buy a used laptop?

There's inherent risk in buying a device from a third party that you may not fully trust, but that risk is in the hands of the buyer to assess, and to mitigate as appropriate. When the average person buys a used laptop from Craigslist, I doubt they're doing a full disk wipe and reinstalling the OS, and they're definitely not verifying the bios or other motherboard-level code. There shouldn't need to be some special case applied for tablets or laptops either. They're all just computers.