Expiration dates are usually there for legal purposes because everyone sues everyone in the US. It's also a guaranteed best taste by kind of thing. Use your best judgement on what it is though, of course. Expired powder should be ok. I've had year+ old Gu's, etc. before without issue, same with powdered drink mixes. Pretty sure my ketchup is like 6 months out and I haven't died. Yogurts a week out are typically fine. Eggs and milk in Europe sits on shelves, not refrigerators. 'Murica is soft. Drink your old powder.
EU almost caused some issues in Poland when they tried banning things like pickles or oscypki because they're just old cucumbers, and oscypki (cheese) use of unpasteurized milk, etc. These things don't have stamped expiration dates. But again, a judgement thing. Fresh bread in Europe is amazing, and only really good for a day. High fructose corn syrup and many preservatives are restricted.