As I understand it, the need for UK regulation only came up due to brexit (before they were in thanks to the common market), so I guess "it's brexit" is sort of

As I understand it, the need for UK regulation only came up due to brexit (before they were in thanks to the common market), so I guess "it's brexit" is sort of right, even if that leaves it a couple of steps? Without it they could have coasted along for a while longer with not much extra effort.