There is a recent new company with pre-washed vegetables "Kleen farm". They use market produce "not green-house" grown. They do a washing under the supervision of a mashgiach, who checks a relatively small amount of samples to ascertain if the washing is working.
Kleen Farm may be the solution to the many if not most foodservice establishments that don't have trained expert mashgichim for checking infestation. It just doesn't compare to the trained expert on site mashgiach or to the positive system which starts with green house grown product.
Numerous food service establishments that have been using the greenhouse grown & superior inspection " Positive" brand have recently opted (or were instructed) to use the kleen-farm brand. Prior to using a food service establishment ascertain what they are using in their menu.