A bankers draft is a guaranteed cheque (in the UK) anyway. For example, if I wanted to buy a used car for £5,000, the buyer would probably want a Bankers Draft so I could take the car there and then, whereas with a cheque we’d have to wait for it to clear which could take up to 7 days. It’s effectively an up-front guarantee from the bank that you have the funds available, and the bank debits the account there and then when you go get one.
That said, I’m not sure how this really applies in this industry. Unless its just a “peace of mind” option – the bank normally makes a charge for a draft to the issuer.