Why do people hate Nickelback so much? What makes them different from other popular bands like Linkin Park, Green Day, etc.? Is it just because they're Canadian or what?

NickleBack may appeal to many, but the majority rules as the saying goes and the overwhelming majority of more vocal proponents voice the opinion the music is bland, generic and commercial, not necessarily in any particular order.

NickelBack.

Even I have cracked a few jokes about the band but I did so not intending any ill will or malice toward the band. Going with the flow at the moment I believe as NickleBack was the topic of the moment.

Joey Chestnut, barred last July, returns to Nathan’s hot dog eating contest - The Washington Post

Canadians are generally likeable people , so NickleBack are most likely ok guys.

I doubt many hate them for being Canadian. I was going to say no one, but never say never , so to speak.

BoB's answer to Is Stan from Eminem’s Guilty Conscience the same Stan from Stan?

Boris Johnson says that “Starmer picked a fraudster for his Cabinet because he is the fraudster-in-chief. And he knows, in his heart, that the whole government is a fraud.” Do you agree with Boris Johnson about Starmer?

Those opposed to the band are simply louder and more vocal than the true fans. A matter of opinions.

Anyway, why are they so despised in comparison to Green Day, Linkin Park, etc ?? To use an analogy, it is like comparing the smoking/stoner crowd in high school, the athletes and finally the unpopular souls.

There will always be that one guy or gal. They may have friends also, so opinions spread, growing in strength , spreading yet further until the humble opinion of one becomes a near fact to many.

Distinctio minus aut doloribus vero minima ut vitae.