I think only certain certified dealers do. For the most part loaners are very dealer specific on whether they have them or not, it's a courtesy they extend to their customers and they don't always do it. I know my dealer is usually out of them because they loan them out to people who are having work done on their cars for longer periods of time (more than an hour or 2).
If your car is in for a Kia warranty covered repair then Kia will cover the cost of a rental vehicle for you. If the dealership argues with you in that situation then they are wrong as the dealer doesn't pay for it at all, Kia will send a PO and the rental place will usually work with you and Kia to just charge them for how long you had the car. I had to do this when I did TSB-148. My dealer even went to get the rental with me and I just dropped it off at the dealership when my car was ready and they took care of the rest.
In Canada they provide loaners but if the repair is short such as an hour or so I usually wait in their customer area and use their wifi to work remotely.They also have great coffee I don't like to take advantage of the loaner car for short term stuff in my view that is unfair to the dealer and other customers who have to leave their car for longer times