They consider DB and DBZ different because they are marketed in the west as two different series.In Japan, DB and DBZ are different only in Anime form. In the West, even Manga readers consider DB and DBZ different. That alone should tell you that most people in the West don’t even watch or read Dragon Ball.
No, they don't. In Japan DragonBall was already popular before it even got to that portion, other-wise it wouldn't have hit nearly 200 chapters in the first place.
How often have you heard GT mentioned?Since 2000, times I've heard DB mentioned (approximate quotes):
1. 2010 "DBZ was good when we were like 5. But did you know some weird people our age watch it still. Yeh it's fucking weird why are you watching a show for 5 year olds"
2. Had a friend who liked DBZ
3. 2016 teenagers discussing DB Super on the bus
4. 2018 young adults discussing DB Super at work
5. 2023 DB Super episodes all on CBBC Iplayer
6. 2023 DB Super advert on a kids TV channel. Showed Goku playing baseball.
Bonus 7. 2011 "no I don't like anime but some gay people in school liked it"
Super (4)>Z (2)>OG