I always assumed stickers were there for marketing/branding purposes.
It always made me laugh because:
a) I coudn't tell you the name of any of those brands, so that doesn't work.
b) I buy whatever fruit is at the shop. I can't go searching for XYZ brand of apples lol
I cut the stickered bit off fruit that I'm eating. I've done enough sports strapping work to know that stickers (sports tape) leave a residue that can be difficult to clean off so instead of trying I just cut it off. I don't want to eat sticker residue.