The USDM mirror glass is sized differently. Euro mirrors are still power adjust, just manual folding. Other than the power folding option (which gets old pretty quick), the European manual folding mirrors have the proper optics for LHD.
RHD mirrors are designed for RHD cars. You reduce visibility and increase your mirror blindspot. Some would still argue they can see out of them... well, let's say I prefer not to be next to them on the road.
If you insist on using them in a LHD car, have a passenger ride and check your mirrors for you at all times :icon_razz