I think it is the other way around. There would be no taxes if it was legal tender. Which it is not, therefore, taxes must be paid.
You're right -- many people get confused, especially if they’re new to crypto taxes. Since Bitcoin is classified as property, that’s where capital gains tax comes in. But if it's considered as a legal tender or currency, we don’t pay taxes on every trade we make.
Maybe that’s also why most countries prefer to label Bitcoin as property rather than currency. Only El Salvador has officially recognized Bitcoin as legal tender, which means there’s no tax on transactions in that area.
El Salvador gave up Bitcoin as legal tender, in return they got almost 1 and a half billion USD in "bribe money" from the IMF.