Scripture makes it clear that the unity is not . . . conflict free.
It also makes it clear that for a time—some say 3.5 years—the world government IS over every nation and people group.
The earlier efforts did not succeed . . . because God’s timing to bring it all to a dramatic object lesson climax had not yet arrived.
For one, Israel had to become a nation again.
A lot of orthodox Jews have also rejected them for similar reasons. There were Jewish states before, who were thought to be the signs of the end. Not saying that this isn't it, but you have to look at the totality of history. We have been much closer to hitting all the signs then we are today..