NO NO NO NO NO NO NO NO that is not the case, it's just that we choose to let Errea make us shirts like that (it might be rules in other markets around the world). There is no FA, FL or any other rule that insists the back is plain on shirts in the UK. Plenty of other teams have stripes on the back of their shirts, Huddersfield, Sunderland and Brentford come to mind immedeatly.
ok colo thanks for the correction, thats why I said " I think"