They have to do that in the UK too, but unfortunately the law doesn't seem to standardise the unit for these comparison values(or it does and is ignored).

If you have two packs of coke cans next to each other, and one gives you a price per 100ml, and the other per can, it doesn't help that much(yes you could multiply the value per 100ml by around 3x, but at a glance the difference isn't obvious).