He must of presumed you were useing the old fashioned method,instead of the perfectly acceptable industry standard.
He should of checked first then he could have told u how to do your job,would have saved him looking like a d.ck.
If the clean is of a good standard then no reason to avoid payment just because he's unaware things have moved on and progressed.I would demand payment.
If he was to get his driveway cleaned he would be the type that prefers to see you on your hands and knees with a scrubbing brush rather than a power washer
Bottom line is he made the mistake