No and yes!
I can't say I have even looked at expiry dates on my
contact lenses when I used yearly ones, but they would last approximately one year and I would have a maximum of two pairs spare so in theory would be within the expiry date.
I have older yearly lenses and if they have an expiry date, then they will have expired, but the prescription is now too weak.
But I was always brought up not to waste things, so if the (expensive yearly) lenses were of the correct prescription, but expired, I would (if not cloudy) sterilise them and use them.
I don't think twice about eating a tub of yoghurt or quark which is 2 months out of date, but still sealed and has been kept in a refrigerator. It is always fine. But I wouldn't try anything like that with ground meat or poultry, which is potentially full of salmonella, etc.
It's about managing the risk and knowing what is OK and what is not OK. It also comes down to how risk averse you are. (I have a cousin in Germany who goes to the other extreme and throws out food even before it reaches it's expiry date and only buys organic food - which I feel is a complete waste of time. I have an inherent mistrust of farmers and very often it is quite impossible to prove the food is in fact organically grown, especially if it originates from third world countries. But each to their own).
Remember, the expiry/use before/sell before/display until dates have different meanings, some legal and others just a guide but with a good safety factor included.
There are usually a few warning signs that things have gone wrong and you need to learn what these are. You have to apply some common sense and knowledge/experience, otherwise, don't try this at home folks!
knotlob