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?

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.

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

NickelBack.

Man accused of writing Trump assassination letters was framed, officials say - BBC

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

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.

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.

Breast transplanted to replace cancerous one in 'world first' operation - BBC

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

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

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.

Don't miss the half-lit first quarter moon rise tonight — Here's what to look for - Space