No they don't, heck there are folks that install pools, do their own electrical, put on home additions without a permit every day. The code does not prohibit you from buying or selling, nor does the seller care if you are going to swim in it or use it as a holiday ornament :lol: My point is if there is as code requirement, as there is in NYS, and god forbid an accident were to occur while in violation, your insurance is useless and the OP can decide if it's worth taking that risk. I'm not sure where you are located, and sorry to all the lawyers on the forum, but around these parts everyone seems to have a relative named "Sue". That said, thousands, if not millions do it and nothing ever happens.
Feel free to read the attached manual excerpt from an intex manual, to see how the homeowner remains solely liable and the seller or manufacturer get around local laws, washing their hands by warning the buyer.