Most of the packaged food sold through major brands and store brands are manufactured at a relatively small number of businesses that pack products under different labels. Yes major brands might tweak recipes or require tighter variance to ensure a certain standard of quality that store brands might not but the difference in products is rarely substantial.
Very little would stop you from buying commercial sized pitches of yeast from BSI or another major yeast lab and repackage or grow up the culture and start your own lab.