The use of money has evolved through history and FIAT money is just one of the last evolutionary phase of money.
"Representative money has now been replaced by fiat money. Fiat is the Latin word for "let it be done." Money is now given value by a government fiat or decree. In other words, enforceable legal tender laws were made. By law, the refusal of "legal tender" money in favor of some other form of payment is illegal."
What "legal tender laws" do you refer to in your post precisely? Did you actually read any of these laws? There are many jurisdictions and many laws that describe the notion of legal tender. If we take the US as an example, legal tender means that the US government agrees to accept the US dollars as a payment for all public debts such as taxes, fees, penalties, and so on. In other words, it is not binding on anyone except public institutions nor is it illegal to decline payment in "legal tender" for anyone other than these institutions. That means that private companies or particular individuals can refuse to take your dollars and you can't force them to accept your money just because you "think" they should.
Some jurisdictions have explicit laws which specifically allow to decline payment in certain situations. For example, you may not be able to pay with high-denomination banknotes for things like a bus fare.