A Kia authorised dealer being able to look up any Kia has some very useful benefits (for the dealer, and thus Kia).
If a customer has moved into the area and you’re now their local dealer they’re more likely to come to you for any problems, including ones involving remote connectivity problems. Being able to see the state of the car on Kia’s systems is important for that.
Is this a tradeoff? Absolutely. Can you make the argument the trade off isn’t worth it? Absolutely. But I don’t think it’s an unfathomably unreasonable decision to have their dealers able to help customers, even if that customer didn’t purchase the car from that dealer.