If you pay to add a feature to a product that was previously not available, sure, that makes sense. But in this case, at the point of the transaction, and they hand over the keys, the ownership of the product is now 100% transferred to the customer. They should and can do whatever they want with their property. A manufacturer equipping a feature because it’s cheaper is frankly not the customer’s problem.
Imagine buying a house but you only get access to certain rooms. They set the price, the customer just pays for it. If they want to cover the cost of adding the heated seats feature, then add it to the starting price.