Does white wine have an expiry date?
Please re-read the text - it says:


  BEST BEFORE: ...


This doesn’t refer to any food safety issues, merely quality. The manufacturer states that until that date, no significant or perceptible deterioration of the sensory quality will happen (provided its stored appropriately). After that date, the quality may (or may not) suffer. It’s not a statement about food safety.

That said, from a food safety perspective you can keep the wine for a very long time, probably indefinitely. Why the manufacturer chose to state a best before date for the white wine only is unclear, probably because whites tend to be more susceptible to flavor changes than red. Note that today most modern wines, especially those that go to supermarkets, are not made for long-term storage, rather for consumption within just a few months after sale. Only some vineyards will still produce wine for future generations. Bag-in-box packed wines are usually intended to be consumed within six months or so after bagging and four to six weeks after opening. But neither of these time frames is set in stone or related to food safety.