This is not what "fungibility" means in terms of accounting & balancing:
In fact, Bitcoin are fungible from a regulatory perspective: As every one USD is worth as another USD, every Bitcoin has same value as another Bitcoin and they are fully intechangeable without any change of value on both sides of the transaction.
Thats the reason why there are NFT - these are not fungible in that sense, as they are not interchangeable one by one, since one 1 NFT may have another value than the next NFT.
In fact, Bitcoin are fungible from a regulatory perspective: As every one USD is worth as another USD, every Bitcoin has same value as another Bitcoin and they are fully intechangeable without any change of value on both sides of the transaction.
Thats the reason why there are NFT - these are not fungible in that sense, as they are not interchangeable one by one, since one 1 NFT may have another value than the next NFT.