It is something which drives me bonkers in Aldi and Lidl. I don't work in produce and never have but from a consumer's point of view, you like to have some kind of guideline on how long the produce would last. I would also argue that with the rocket (which is likely to be washed I'm guessing?) As it approaches the end of life, the leaves will become more limp and there is already a known salmonella risk from damaged leaves in bagged salads in any case. Whether or not that grows to significant levels is going to be down to shelf life.
As for other produce? Honestly when I shop in supermarkets like Aldi and Lidl where there are minimal shelf lives on produce, 1 time in 3 I will find another, high risk, food item on the shelf which is out of date. Last time I went it was cream. I am one of "those people" who always take it to a member of staff to throw out (better than if I contacted the EHO as it's an offence). But if the staff aren't noticing the food with use by dates is out of date, will they be carefully checking the lot codes on the produce? From the limp evidence in my local store, I would wager they aren't.
So should you legally? On the bagged salad from a food safety point of view I'd say yes. From a legality point of view in terms of labelling, I've looked it up and it's debatable for the rocket but clearer for things like punnets of berries.
This is the guidance for the legislation:
And this is the pertinent "bit":
Showing the ‘best before’ or ‘use by’ date
You must usually show either a ‘best before’ or a ‘use by’ date on the packaging or label of pre-packed food products.
Only show a ‘use by’ date where there is a safety issue with eating the food after this date. It’s a criminal offence to sell food that’s past its ‘use by’ date.
Read further guidance on date marking
You don’t need to show a ‘best before’ or ‘use by’ date, but you must include a lot number on:
- fresh fruit and vegetables which haven’t been peeled, cut or similarly treated (except for sprouting seeds and similar products, like legume sprouts) My comments here - if your rocket is washed, then I would argue it's been "treated" but perhaps check with your legal department.
- wines, liqueur wines, sparkling wines, aromatised wines and similar products made from fruit other than grapes
- drinks made from fermented grapes or grape musts
- drinks containing 10% or more alcohol by volume
- baked or pastry goods which are normally consumed within 24 hours of being made
- cooking salt
- solid sugar
- confectionery made almost solely of flavoured or coloured sugars
- chewing gums and similar chewing products