You have a point but it's 0.5g each candy so they're in the area of rounding errors. And as every programmer knows just one rounding error won't bite you, but when (often) it gets multiplied...
The EU probably requires calculating energy in kilojoules (which are 4x calories) and then converting back to calories which results in different rounding.
I believe the US allows .5 to round down to 0, while I've seen EU labels list e.g. .5 g of fat, so I wouldn't be surprised if they require it.