Regarding scenario #1, it is irrelevant if the amount is $50 or $1000. My point is, you have no recourse. Credit cards won't protect you from fraud in this case.
Anyways, debating the effectiveness of consumer fraud-protection is quite beside the point, since Bitcoin offers absolutely no fraud protection and very circumstantial utility (i.e. the ability to make anonymous or pseudo-anonymous payments).
"If your Password or PIN is used in such a transaction, you will be liable for the full debt, including interest arising from such use" Source: http://www.scotiabank.com/ca/common/pdf/borrowing/revolving_...
In other words, if a thief somehow steals my PIN, I will be liable as a customer. If you still don't believe me, read any of the stories reported by journalists explaining how banks reject fraud claims when the PIN was used: http://mymoneycounselor.com/card-fraud-blame-shift Merchants may be responsible for verifying the customer's identity, but often they don't. This is why credit card fraud is prevalent.
> debating the effectiveness of consumer fraud-protection is quite beside the point
On the contrary, this is important in this debate. You can't use "zero-liability" as a reason why credit cards are superiors to Bitcoin when I prove to you customers are actually held liable in many cases.
Bitcoin can be superior to credit cards, because when the wallet is properly secured (for example a passcode-protected hardware wallet), theft and fraud becomes increasingly unlikely, whereas credit card fraud continues to become a bigger and bigger problem, and banks increasingly shift the liability toward customers as I documented above.