No one cares what the currency is fixed to if its not redeemable. Like saying you have insurace but the insurance company wont actually cut a check.
In theory, but not only did the US abandon the gold standard from 1932 to 1944 Roosevelt actually made it illegal to own gold in the 1930s, the very opposite of making it redeemable.
As a result, any ability to actually redeem becomes dependent on the next political whim. Besides which, gold itself is actually pretty clumsy to use as currency for most transactions (as is cash anymore). Even when redemption for gold is defined and possible it usually not particularly useful. Plus I can redeem my dollars for gold whether there is a standard or not. It is just whether I redeem at a fixed or market rate.