The BBC reports that Tesco are updating the signage on their express checkout lanes. Apparently there is some confusion about if the signs should read “10 items or less” or “10 items or fewer” so Tesco are going with “Up to 10 items” instead.
There is no confusion. Waitrose have had it correct for a long time now and it comes down to a simple rule: less is continuous, fewer is discrete. That is to say, if you can quantifiably count something use “fewer” and “less” otherwise. For example, you can have fewer items but less shopping.