How come nutrition labels claim less nutrition than is probably in the food?!

How come nutrition labels claim less nutrition than is probably in the food?

ive always wondered how, a foods nutritional label will list a limited amount of vitamins and minerals and sometimes none, when in fact it contains more.

for instance, i love french onion soup. on the back of my soup back (its a good soup with real onions), it says 0% of everything. but i know on some level the onions must be nutritious, even when they are dried as in a soup.

thanks.