> Would they?
By my experience, yep. Especially in our modern era, we are attracted to big payoffs and quick solutions, and not as motivated by morality. Here's a fun (or frightening) little tidbit (
https://www.elitedaily.com/social-news/ ... rs/1346072).
> Why must this be so?
It's not that it must be so, it's just the human condition and more so our modern mindset.
> Also see my other question about why God would create a world in which people are drawn to evil.
It is of benefit that humans (whether through natural evolution or investment by God) have a sense of right and wrong, so that survival is not only possible but enhanced. For the sake of this discussion, since you asked why
God would create in such a way, I'll take the conversation in a theistic direction.
If this is not the best possible world (a world in which life-enhancing behaviors were impossible), then such moral choice to make a positive difference in the world is an asset. For this, a being needs three things: knowledge of the good and its benefits, the ability to make such a choice for good/benefit, and the power to play out such a choice. A world where choices only make things worse would hardly be worth having.
Knowledge of the good and its benefits implies or necessitates commensurate knowledge of alternatives to that direction. So God could be motivated to make such beings who have knowledge of the alternatives and some power over themselves and at least somewhat over their environs, both people and circumstances. They are able to participate in determining the destiny of things. That there should be beings with such motivation and control is good. They would be higher than mere robots, higher than animals (who are more concerned with and capable of power, instinct, and survival), and more like an image of their Creator—little creators.
Such creatures would by necessity be of limited knowledge, power, and choice, for another being of unlimited attributes as God Himself would potentially be able to stop God doing things, and it's logically contradictory to have two omnipotent beings in competition with each other.
A creature with limited knowledge, power, and choice would not by necessity be perfectly good. His limited knowledge may not always perceive the right. His limited choice may not always select the right. His limited power may not always effect the right. Because of his freedom, he has no intrinsic inhibitions to avoid what is wrong and always do what is right. For that, he would have to have the good and the right perpetually forced on him.
What seems to be the only logical and rational option is creatures who are created almost morally good from the start, who have a knowledge of what is right and good, and who have considerable choice over a period of time of self-determination.
An omniscient being such as God would always know to choose the right and an omnipotent being would have to power to always do what is right. Those of limited knowledge and power do not have that same capability, by necessity. Sometimes he will choose the wrong in ignorance, sometimes he will be in the wrong by lack of power, and sometime he will choose the wrong for some perceived (though misguided) benefit.
> In addition, can't the loving relationship itself be the payoff?
Yes. This is why I have chosen Christianity. It's not for health and wealth here in this life, but for the relationship with God. That's the prize (Philippians 3.7-8, 14).