You can either categorize merchants by MCC or by name.
So when enabling cashback for the merchant “LIDL” they just put that in the list.
For Star Alliance they would need to add every airline. This would only apply then when purchasing flight tickets directly from the airline / via BSP.
All aside, 3% on any purchase without a max limit for EEA issued cards is not reasonable for any card issuer.
For consumer cards the card issuer can only charge 0.02% (debit) and 0.03% (credit), so anything more than this a card issuer loses money.
For U.S. issued cards, no problem since they dont have that (very good for the market) % limitation.