agreed- easy enough for them to do a blanket STOP on large grocery purchases during a promo. But in general I do not think grocers are giving L3 data
In any case, I always throw in a few grocery items with the GC as an additional mitigation
I checked all the grocers I use for any purchase and all were sending L3 data. Right down to the items being purchased. Even small grocers.
You can't datamine if you lack the data. Credit card companies and banks do extensive research for marketing purposes.
Don't assume that the information is not being provided. It may just not being processed to our detriment.