The value of one coin of one denomination must not differ from the value of another coin of the same denomination.
fungibility is not as you think
all money is treated differently and always has been
if you get money in your account from an employer. that amount gets taxed as income tax
if you get money in your account from an investment. that amount gets taxed as cap gains
if you get money in your business account from customers. that amount gets taxed as corporation tax
if you want more than $500 from an ATM you have to talk to your bank
if you want more then$1000, $10000 expect reports to tax offices
doing a wire transfer of $30k using a business account gets treated differently than a minimum wage person doing a $30k wire transfer of his life savings
what most people dont realise is money is not fungible. its just when only handling small amounts like $100 in you back pocket. your not really a big concern for authorities to watch compared to someone with over $10k in a suitcase crossing a border.
and yes different rules apply if your using cash, debit or credit. heck even mortgage amounts are put into escrow whilst paperwork is done.
money is treated differently and always has.. welcome to the real world