Sorry to say it would never surprise me if it is B related and the reason I suspect why mercedes does not offer their excellent eco coach appin the UK.
But having said that the EU regs never stopped countries having additional demands if they wanted and I do not think there is a europe wide child in car approach for exaample🤷♀️here children have to be a certain age to travel in the front seat.
I can see the UK going backwoards rapidly if it is Sun readers they are asking to define what regs to get rid of😤
I wish I could argue with the sentiment you make. it's very hard to find evidence that would support near anything good about B.
And wouldn't it just be another nail in the coffin for this ridiculous small island (or rather it's leadership, not it's people) to find that super crazy new functions in a new car that one works hard to afford, are blacklisted because of that broken relationship.
Sure there's always cross boundary specifics, it's what make us this mad bunch of crazy interesting people and countries. But it would be nice if the tech was allowed to flourish better and wider.