Because we havent fully explored the deepest depths of the earth/ like we only know about five percent of the ocean/ so we fully don't know the earth/ there could be huge monsters laying in wake for the right time to creap from the bottom of the ocean and pulverise all in its path/ so yeah thats a reason we don't know what earth fully looks like

It all depends on the reasoning behind it/ i'm not with it or against it/ if that person knows they can't take care of a child/ than yeah don't make that child suffer through his life/ but if its for no reason and they just don't want children screw them, you are taking care of another lifeform that resembles you/ most of the time making them a better person/ so i am neutral on the situation