As an aside, I have noticed some clients adding a note saying "no voucher" or "full fare paid" or some such to some Free Now jobs. Maybe they think service has declined because drivers are made give promo code / voucher discounts?
That's interesting, most customers don't know
(and 99% don't care) that it is FN that take the hit on discounted fares.
Most likely the customers line of thinking is that they will get a cab faster if they do not use a voucher ?