Don't be silly, human beings are on both sides. Sometimes alliance is grouping sometimes it's horde. There are players who play for honor, prestige or whatever drives them and there are people that just want higher ilvl or more adequate stats for their spec. There are way too many players and servers to generalize.
It's really amusing to read how people make up these dream scenarios that the Horde plays with honor and does 1v1s but the Alliance groups up and ganks players. The delusion is superb.
Both sides avoid fighting when they see the other faction.
Both sides group up
Both sides do 1v1s
Both sides gank the other faction until they leave
Both sides do all the same things because they are filled with individuals. Some fight fair, others don't want to fight at all.
Throughout all of BfA the Horde has bullied Alliance out of warmode and turned it into Hordemode. It's really funny that a Horde player now complains about what Alliance experienced for 2 years.