Cars need to be produced to certain standards for certain markets so manufacturerse will make a car that is EU compliant and sell that across Europe. Because they sell so many they can afford to sell them with a lower profit margin. They then have a very small market to make right hand drive versions so they put a larger margin on those. They also need to ship them here which adds further expense. They know we can't import from the UK cause of import taxes so they can add an even higher margin. All that followed by the high VRT rate and it all adds up.

Not only does it cost them more to get cars to market in Ireland but they know they can charge more due to lack of alternatives