I don't know if it's legally required, but that's also the standard here in the US. One problem though is the units may not always be equal. I was buying canned

I don't know if it's legally required, but that's also the standard here in the US. One problem though is the units may not always be equal. I was buying canned coconut milk this weekend and among all the different choices were $/pound, $/gram, and $/liter. It's easier to do the math from scratch yourself at that point.