I find it interesting that you mention this considering how fast the ultra orthodox Jews in Israel also breed. Also, since they study all the time, they are also below the poverty line and are heavily dependent on government welfare. But I'm sure you forgot to mention that group and overlooked the fact that they are not given these birth control pills. If they were offered these pills, it would rip Israel apart. But since they are of European descent I guess it's ok
As for the exodus from Ethiopia to Israel, Operation Moses was done for the same reason Israel will take any Jew, whether real or imagined, from Europe. It is mainly to bulk up the state and "save" Jews from hostile governments. Finally, these groups were literally cut off from the rest of the Jewish disapora when they left Israel a loooooooooooooong time ago. They first settled in Elephantine. Facing a hostile Egyptian Empire in the north, they went east and settled in Ethiopia. Seeing as they were the minority, they adapted most of the customs of the natives.