My guess about the steering wheel is that putting it on the USA side would mess up the composition. ERK wanted the babe front and center AND the guy to drape his hand over the wheel. With the wheel on the left there'd be no draping. Reversing the camera angle means the woman would have to be at the wheel for the man to drape on it. ERK could always argue that the couple is in a British sports car, which were sometimes imported with right hand drive.
In an interview Harry Harrison mentioned using this dodge. During his comic book artist days Harrison was given a wordy romance script in which a couple were in a car. In every panel the man, who was driving, spoke first. For the ample dialogue to read in the proper order the balloons would have to be stacked awkwardly with confusing pointers. Harrison put them in a British sports car. Problem solved.
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Realistic Romances 16