Odd example - Britain has a huge alcohol abuse problem and staging interventions on alcoholics who are spiraling the plughole is probably the most politically acceptable application of financial surveillance one could think of.
One issue with doing this is that blocking gambling is usually done by the merchant classification. Betting shops are easy to categorise and identify from their merchant category.
Alcohol can be bought from a supermarket, or corner shop, or off-licence. Other than dedicated off-licences, the merchant classification wouldn't be enough to let you block gambling transactions.
To do this effectively, you'd need support in the EMV spec to allow the card to tell the terminal it is unable to pay for goods in a given "category", and have a standardized list of goods categories, and let the POS system send a list of categories to the card before it tries to authorize the transaction.
Otherwise I don't see how you could "delve into" the purchase deeper than seeing it's in a supermarket, and not knowing if it's for alcohol or other items.
