grafted trees

bakerbhoy

Quick question.
I was looking at some trees at a garden center during the week and the following were all grafted onto root stock.
laevigata 'Paul's Scarlet'
platanoides 'Crimson King' red norway maple
platanoides 'Drumonii' variagated norway maple
Aesculusx carnea 'Briotti' red chesnut

Is this normal or can they be sourced in full form ?

greasepalm

a lot of things are grafted onto rootstock as it has a better root system so instead of sending roots out say 50+feet could be container grown and growth is put into the grafted section which then can be a 1/4 of the size of a natural seed produced specimen apple trees,roses even cacti have been grafted onto stock plants.