Ok I will try and rephrase.
It is really easy to identify if a hard drive has a wallet on it or not. You just use find o Linux or search on windows. Admittedly recovering is a bit harder (In practise you'd set up a new wallet and transfer them out) just like how you would for recovery.
it depends. you may be able to find wallet files, but what percentage of them will be unencrypted? that adds another layer of risk here.
the earliest wallets are less likely to be password-protected, but they are also the most likely to be inaccessible due to data corruption. years of storage under less-than-optimal conditions (and outright exposure to the elements) can easily foil these plans.
If people would do it or not is an interesting question, the odds suggest it would be a bit like buying a lottery ticket (some people do) although in a software case you'd not need to actually spend anything.
As to where you'd find these hard drives. Auctions,eBay,car boots,neighbourhood swap sites freegle/Freecycle, removing from PCs abd yes the dump, I've got equipment from all of them. (One had a wallet which got me into bitcoin)
i agree that as price rises, the cost/risk to engage on wild goose chases to recover bitcoins becomes more sensible. for example,
this guy is fighting to get the government to allow a search of a landfill for a hard drive containing bitcoins.