Undewriter's Laboratory is a private company. The is no government mandate or law of any kind stating UL approval is required.
The entire electrical code is written for electrical contractors. So they all are 'on the same page'.
The only thing that can happen to anyone for violating the 'code; is your permit may not be approved, or you may have to tear out the work and redo it WITH a permit.
No one is going to jail... Because the CODE IS NOT A CRIMINAL LAW. other than laws governing HOW electrical work BY electrician is done.The mysterious scare tactics claim about insurance companies is always fascinating. That somehow they will n cover audiophile gizmos. Yet if that were true.. you wold see many articles and stories about actual refusals to pay claims. there ARE NONE. Look at for example flood insurance and the endless hassles. All sorts of stories. Then no stories about audiophile toys caused loss of coverage.. Where? FIND ONE.
So all the talk of some folks making claims of insurance problems? Not true.
The code is for electricians. Some electricians may say due to their own liability, no I will not install anything not UL approved. There are no laws saying you cannot have it. But if you sell you home, best take it out. Mainly to avoid lawsuit crazy lawyers. Example: "They sold us this house and when our little Tommy was sticking multilple screwdrivers into that unapproved AC duplex with his friends, he burned his hand off. And since the folks who sold us the house have money, we want it. all of it. For poor Tommy's hand." Or they go after the electrician, wo hopefully has even MORE money..