To anyone who's ever patronized a laundromat, a sign to that effect is very familiar. Another (generally unwritten) house rule is that you're not allowed to wheel the laundry carts out the door, certainly not so you can air out your veggies. Typical for this sort of minor incursion onto public space by a private party, the produce was unlabeled and unattended, and not stationed immediately beside any business that might receive a citation.
See also previous sightings of streetside greens and oranges.
Drying vegetables
Sunset Park, Brooklyn