I'd say the car entering too
The one driving in
The car entering
One driving in it’s their continuous road. The other is entering a new road
The one entering as the car from the right has to cross a main carriageway. The car from the right isn’t on a main route depicted by the junction lines on the junction opposite. So the car on the main carriageway has courtesy of the road. However, the car park owner I would think is obliged to make the junction clear as if there was an accident, they could argue that was no sign to stop to give way. I don’t more of that is a legal requirement in car parks though.
There’s no obvious markings but I’d say the car entering just as they are not changing their direction of travel