What might be a purpose of the mere exposure effect from an evolutionary perspective?

To avoid unfamiliar and possibly dangerous stimuli.

Explanation:

The mere exposure effect is a psychological phenomenon by which we usually reveal an inclination for things simply because they are known to us. It refers to a situation in which a certain stimulus has been available to a subject’s perception, either consciously or subconsciously.

It was first proven by the Polish-born psychologist Robert Zajonc, who performed a seminal experiment in 1968.

the reason the welfare system causes so much of a burden on its recipients is because the welfare system does not give its recipients any real tools to actually get out of poverty. the welfare system has embedded poverty deeper into society and has made it harder and harder for people to escape poverty.

in other words, it stoped the poor, and now its making it worse.

hope this . : )      

and im sorry it took so long for your question to get answered