The same as in the USA and many other countries IRL: Fundamentally different belief systems.
By "fundamentally" I mean there are core values each side believes in, the beliefs are technically unprovable as right or wrong, and part of their belief system is that global ramifications exist if their system of belief is not adhered to.
For a current example (and it is just an example, I wouldn't use it in a story) consider climate change: Many believe in it absolutely, they buy into the science and trust the scientists. Of course they have not examined the data themselves, or done the calculations themselves, or bothered to check the claimed chemistry themselves. They don't know how, they don't have the time, and they don't believe a fraud of that scale could be committed. But it is something they (not the scientists, the non-scientific believers) are taking on faith, or simple belief.
On the other side are many people with a different flavor of pure faith and belief: A belief that God would not ever allow Man to destroy the Earth, would not abandon the children he loves, and a pure faith that the scientists must be wrong or intentional frauds seeking money for their worthless studies, because their God truly loves them and will simply not allow the Earth and billions of innocent people to die.
Which means, all taxes, restrictions, laws or whatever else aimed at preventing climate change or global warming is really theft and slavery they will not tolerate.
A similar dynamic plays out between people in favor of regulating business, and those that believe free markets should reign. Neither belief is provable and the logic on both sides is rife with problems, laughably bad statistics and idiotic economic math (I am a mathematician and statistician btw). Or between socialists and libertarians.
All of these are systems of faith sprung from different fundamental beliefs on how the world works, how economies work, how politics should work, what is moral and what is not, and different religions (or rejection of religion).
Two heroes can go in search of treasure for different reasons: Alex goes because it is his chance to help the poor in his village, Baron believes in the merit system and believes anything he gets should be his, he worked for it, and although he has a moral system, it does not obligate him to help anybody without some kind of incentive for him to do so. He has a deal with Alex to split what they find 50/50 and he will honor it and if necessary demand by force of arms that Alex honor it too: A contract is a contract for Baron, whether good or bad, in retrospect, and he truly holds himself to that standard. Baron believes the down-trodden are on their own. Alex truly believes he, and everybody (including Baron) has a moral responsibility to help others that need it.
Together, they can go treasure hunting: Alex will risk his life to save Baron because it is the moral and right thing to do, without a single thought toward their contract; in fact he sees Baron as his friend and brother in arms.
Baron will risk his life to save Alex because he sees it as being part of his partnership contract with Alex; nothing more. He does not regard Alex as a friend or brother, it is all business, and without that handshake agreement to honor, he would not risk his life and would instead watch Alex drown in the river.
Both men are honorable, neither is a cheat, but their belief systems are so different that eventually, once the treasure is secured, Alex may feel betrayed by his "friend" and "brother" Baron. But Baron is innocent; he feels their business contract was successfully concluded when they split up the treasure and went their separate ways. He owes Alex nothing and Alex owes him nothing. His refusal, say, to come help defend Alex's tribe from invaders is just business, Alex offered him nothing. So now Alex's wife and children are slaughtered and he blames Baron. Baron tells Alex "Blame yourself, you fool! If you hadn't given your money away, then like me, you could have built a castle to protect your wife and children! They were gutted because you, Alex, do not know how life works!"