Why would a chain retail employer take more than a month to give you shifts if at all?

Is there some advantage in having employees just doing nothing? I got an offer in early june, got paid for training and induction, got the uniform, and then, radio silence.

I chased them up on the phone three times and today, when I called yet again they asked me to send them an email at a specific address. It's been over a month after I got the training btw.

I realise I need to look for new job obviously as these idiots are pulling my leg. But can someone explain why would they bother with recruitment if they don't need staff?