If the Cadenza uses 1157 bulbs, then I would imagine you guys have the same thing as the Optima then. What you are describing with no wires coming out is just the way KIA chose to design these setups. They use surface mount electric contacts which make contact with the electrical when you plug in the plastic clips and twist them.
There is no such thing as an error free/resistor free switchback bulb, not yet anyways. Many companies have tried in the past but they all end up overheating very fast.
The dual element of the 1157 bulb on the Optima is so you can have parking lights on and when you use the turn signal, it functions then as a blinker signal.
Does the Cadenza not have the parking lights come on in the same section where the turn signal goes? They would be yellow obviously and not white as in the pic.
See below: