it really doesn't help that you being non-american, could conceivably be talking about any one of about 20 different 'pounds'. America itself only uses the avoirdupois pound, but if you thrown internationalism into the mix, it could be a troy pound, an ISP or a non-US avoirdupois pound, maybe we're even talking about a russian pound... and that's all before we get to pound-mass vs pound-weight/pound-force
here, let wikipedia muddy the waters even more for us:
https://upload.wikimedia.org/wikipedia/commons/thumb/0/0a/Co...
People who are serious about cooking know about the volumetric units used in cooking and the relationships between them. (teaspoons/3 = tablespoons)/16 = cups.
But your American friends who don't know how many ounces are in a pound? I hope you're kidding. That's basic stuff, taught in elementary (primary) school.
It is because we count with base 10 numbers that metric is easy and imperial is difficult.
In the EU, the same thing exists, but it is always per 100g or per 100ml. No exceptions. So comparing two food items is always super easy. I don't know why the US allows this idiotic loophole of per serving.
You can see the prices per unit on their websites:
https://www.tesco.com/groceries/en-GB/search?query=bottled%2...
Not sure if this is required by regulations or it’s just the supermarkets being customer-friendly though.