commodity futures--I just don't get it

Schweser Book 4 page 60 top of the page "The owner will only store the commodity if forward price is greater than or equal to the expected spot price + the storage costs But page 65 right before the example "For the investor who doesn’t earn the convenience yield, cash and carry arbitrage implies that F<= expected spot P+storage costs anyways I just don’t get it and I guess just to have to memorize it and stop waisting my time

Isnt this just what defines the arbitrage relationship? The owner will store if the futures price includes the cost of storage; the investor will only accept if it is less than the cost of storage plus buying on borrowed money, therefore the futures price needs to be approximately equal to the future value of a loan for the underlying plus the FV of storage, minus any benefits like convenience yield. What I could use is a better set of examples of convenience yield. I gather the elimination of business risks that can be traced to insufficient inventories is one example; are their others?

maybe looking at the formula will help: F = Se^(risk free rate + storage costs - yield)*time yield being dividends or lease rates or convenience yield depending on the underlying. so the owner will only store the commodity if F > Se^(r+storage)*t;

I understand the owner will only store the commodity if F > Se^(r+storage)*t; What I don’t get why it becomes Se^(r+storage-convenience yield)*t

So reason it out - The difference between soybeans and (meal and oil) is called the “crush spread” and it’s all about production costs and delays. Suppose that it is peak cow growing season and you have soybeans (which cows don’t eat cause it costs too much) and meal (which cows do eat because you’ve removed the part that costs too much). The meal would have a significant convenience yield because hungry cows can’t wait until the next delivery month. Beans might not have any convenience yield becaause they still need to be processed,