My understanding is that doesnt work.... why??

 Your broker can borrow your shares if you dont fully own them.  EG.  For anyone using margin to buy say  10,000 shares.... you dont own all those shares.... so Schwab or E-trade can borrow your shares to fill a shorters order.

But if you paid cash....not on margin.......they can not borrow your shares..... ......... Some Brokers can call/send a letter requesting to borrow your shares...... they will pay you a % interest or this. But dont have to allow them.

 But only shareholders on cash with alot of shares get approached by their broker for this....... i've seen it before on another stock....