Maybe in pagan cultures, but what single instance of premarital fertility-testing is there in the Bible? It sounds so much like modern rationalizations for premarital sex - “We have to test each other out before we marry so we know we’re compatible.”
Literacy comes much later. The development of societies above the level of the peasant village comes even later.
Let me give you the big surprise of our life ~ peasants were not stupid ~ ignorant certainly, but not stupid. A man couldn't farm without his own farm hands. Only the most fortunate of men could go through life without sons, or daughters who could attract somebody else's sons.
Just the way it was.
Did you know that in the 1700s the Colony/Nation/State of Maryland had only 78 marriages recorded! Now what do you imagine those folks were up to?
Then there's the case of Adam and Eve ~ now how'd that happen eh?!
In this brutal age of rough people let us celebrate the arrival of another new life. The rest of it is just ceremony.
Didn't need them we had concubines :)
I suspect the fertility thing was mostly about the Royals.