It may be the same salt you are using, but it is in totally different quantities and yes, quite a lot of that salt will get poured away when you strain the veg or pasta, but it also comes down to giving people the choice of salt. If you have cooked the veg in boiling water which has had salt added to it, for me, the veg tastes salty (I hate the taste of salt because of years of having to brush my teeth with it due to being unable to use toothpaste as a child). Also some people (like myself) are very sensitive to salt. Too much of it and my legs will swell around my ankles, yet my OH can eat it quite happily (or anything that has a high sodium content) and have no issues at all.
I do find that fresh pasta is nicer with salt added to the water prior to its brief cooking in boiling water, but this seems to me to be simply because the fresh pasta absorbs less water (I'm guessing through osmosis - that being the only logical explanation for my observation) than when cooked in saltless boiling water. However, I think that is about the only thing I will add salt to when boiling in water.
Omelettes I will also add some salt to prior to cooking because eggs to see to benefit from a small amount.