Why is zakah not obligatory on olives, even though they grow them to trade in them?

The questioner : ... regarding olives, it is trade, O Shaykh, because they planted them on the basis that they would trade in them, so why is zakah not obligatory on them, I mean?

The Shaykh : I told you that the fixed zakah is not obligatory on them, but the general zakah is obligatory, as He the Exalted said: This does not mean that if a person has one hundred olive trees, he does not give anything from the olives at all. No, but he does not give a fixed amount, as is known for the three or four items that he (peace and blessings be upon him) mentioned to Mu'adh ibn Jabal: and he mentioned wheat, barley, dates, and raisins.

The questioner : Like oranges, O our Shaykh, just like olives, yes.

The Shaykh: Yes.

The questioner : ... the people divided into three groups: the Shi'ah, the Sufis, and the third type are those who do not know what anything is about the Fire, and we are there.

The Shaykh : Excuse me, what is the third type?

The questioner : The ignorant ones, no... and not the Shi'ah.

The Shaykh: Allahu Akbar.

The questioner : So we are present there, and we are confused: do we call the Sufis, or do we call the Shi'ah, or do we call these ignorant people? So we hope that you will answer.

The Shaykh : Well, I think, may Allah reward you, that this question...