> Even the word contract is in smart contract
The word Fun is in fundamental, doesn't make it fun.
Contracts are written in specific ways, either because they are directed by law, or because they are trying to reference law to make something happen (or not happen).
Convention, rulings and specific laws have been built over time to make sure that certain practices are stopped or encouraged.
In the UK(and therefore possible common law), there is the concept of a verbal contract, which is implied or sealed when money is exchanged. For example when I buy something physical from a website, its distance selling, which means that regardless of what the site says, I am entitled to send the item back within 14 days and get a refund(with some conditions).
Smart contracts are not either smart or a contract. its an implied contract at best, which means the legal outcome is undefined. the onus is on you to prove that it was a contract, and that your contract complied with the relevant implied laws for the transaction you are doing.