Aren't credit cards too slow to be considered instaneous?  Merchant isn't sent funds for 48 hours and funds can be taken back up to 180 days.
Both BTC and CC provide notification of a transaction within a few seconds.  BTC are confirmed in ~1 hour, CC are confirmed in 2 to 180 days.  Trying to execute a double spend in person in an environment where one can't guarantee execution time (like grocery store checkout line) is incredibly difficult.  Stolen credit cards can easily be bought online for far less trouble.