So why is it that people of different cultures who seek God find different Gods, then?

Muslims find Allah. Christians find Yahweh. Hindus find Brahma, Vishnu, Shiva, or one of their avatars.

If there were a God, why wouldn't they find just that God and nothing else?

And overall, as I mentioned in my previous comment, the idea that God cannot interfere in the world nor directly reveal Himself makes nearly all of the Bible, both Old and New Testaments, false.