Friends or family can't read your mind, but they can steal your physical key.
People putting pins on their phones or password on their laptop are not afraid of being pirated. This is a vague, abstract threat to them. Becoming part of a botnet is really not important to them, and they getting their credit card stolen from the web is really not credible enough for non tech saavy user.
What they are afraid of is other people looking at their stuff. Internet history. Pictures. Their clear text personal document.
Beside, a key is annoying. Where do you think they will store it when they travel ? In the same bag than the laptop. So you steal the bag, you steal the password.
Not only infeasible - physically impossible, in fact (barring quantum computers). Just 128 bits of entropy would take 1e16 (10 quadrillion) years to brute force at 1e15 attempts per second. :)
And of course you need a duplucate for the key.
Your example of people leaving the key with the laptop is a good example of one of the potential flaws, but just like if your credit card gets lost or stolen, you report it and it becomes unusable.
I agree that there is room for 2FA, but this is also surely preferable to the current system.
This is a false equivalence because knowing someone's credit card data only allows you to do one thing which happens to be pretty detectable: using their credit card for yourself.
Knowing someone's password allows you to know one or more of their secrets, including many applications that are virtually untraceable for the average user. So the deterrence factor is much lower in the second example making it much more likely that a nosy parent / sibling / SO will take a person's key.
There's no reason that using a password/key can't be just as detectable as using a credit card.
Also trying to trace logins application side is rather foolish IMHO, this should always be done at the authority that is granting the authorization.
That's not my point. The status quo is that people get alerted if something uses their credit card inadvertently and don't have similar alerts for uses of their password other than in a handful of situations like Gmail logins.
It's definitely not impossible for people to keep tabs on their logins, but this isn't how the Average Joe operates.
Plus, there's also the obvious solution for potentially stolen and misused keys .. just add a PIN.