When the US does this we will have to amend our currency to read this note is legal tender for all debts, public and private – unless we decide they are too expensive.
Australia’s Liberal Party government has announced that it will soon be illegal to purchase anything over $10,000 AU ($7,500 US) with cash. The government says it’s, “encouraging the transition to a digital society,” and cracking down on tax evasion.
Source: Australia Bans Cash For All Purchases Over $7,500 Starting July of 2019