Leaving aside all the import paperwork stuff, I think the main problem with having a Right Hand Drive (RHD) car here in the land of LHD, is just that: the car's got the wheel on the wrong side!
Yes, I've driven on the left and the right and adapting is not hard, but I wouldn't want to drive in the ditch and not be able to see to pass all the time. Left turns would be really interesting.
The exhaust manifolds, brake plumbing and other bits are wonky in an RHD car built in an LHD country. Apparently working on an RHD heater core is easier, but really, I bet the Germans had some wicked local LHD cars, and Portugal and Italy got a super-duper 318 that sounds interesting.
Ask me about the 'Adaptadors' I drove in Bolivia; used RHD Japanese imports that had their steering columns and racks flipped over so the wheel came out of the (left side) glove box and only my passenger knew how fast we were going. And the brake mechanism and throttle linkage
... I'm told they're illegal now.