In the Uk they list the nutrition numbers "per 100 grams or mls" rather than "per (teeny tiny) serving" so our counts are more accurate.

So from the Hellmans Mayo label in my fridge
100g (which is about 7 tablespoons) has 3g net carbs/sugars, making each tablespoon a bit under 0.5g net carbs.

If I recall correctly, in many countries they are allowed to say "zero" if the true number is under 0.5, so could legally claim zero carbs for one tablespoon of it, so anyone not aware of this might use say 1/4 cup thinking they were adding no carbs when in reality they were adding just under 2 net carbs.

Not a huge error but over several meals would add up!!