Interesting, my Dh works for an instant lawn company and of course our lawn looks awesome! We don't water it but it does get fertilised.
We have a vegie patch too, albeit a small one atm since we are novices and some of our crops have failed. I would say the lawn takes LESS time to look after - we are always doing something in the vegie patch - either pulling out plants that didn't grow or watering, fertilising, haversting, replanting. My DH mows our lawn once a fortnight and on average it takes maybe half an hour to mow.