The Euro regulations cover all kinds of vehicles, new bikes are now Euro5 as of this year, IIRC cars are now Euro6.
One way or another most of the developed world adopts these same standards under different names with the exception of the US.
Remember how Europe got fuel injected 750 Shadows in 2007 and the US didn't get them to 2010.
The 750 Shadows disappeared from the rest of the world in I think 2017, but still linger on in the US.
I think the Shadows were too old tech and probably not selling enough to make an update worthwhile for Honda.
It is not necessarily a V-Twin thing as Suzuki still sells the SV650 and Vstrom in Europe, although I hear replacement parallel twin rumors, but that seems to be causing a bit of resistance amongst fans, so Suzuki may continue dealing with the added costs of V-twin compliance for at least a while. Honda, Kawasaki and Yamaha seem to all be committed to the cheaper to produce and make comply inline engines.