Because the cashier doesn't know until after everything is rung up that the customer is going to whip out an EBT card. This then forces the cashier to go back through all the bagged items to figure out what is ineligible, all while the customer rages at them.
The customer can walk away, leaving all the items behind, forcing the store to return items of now-questionable integrity back to the shelf, especially meats, while the customer simple goes to another store and tries again.
Sounds like a great idea, with the best of intentions, what could possibly go wrong?
The alternative is to have the EBT card presented beforehand and then have the rejected items flag as they're rung up, leading to multiple confrontations as each gets flagged.
In addition, stores that put up signs in the aisles are playing pretend. Customers move items all the time and someone coming along and picking up an item that has no sign nearby is going to be pissed when the cashier tells them it's not approved for EBT.
Producers do NOT want to label their items "EBT Approved" or "EBT Unapproved", especially since some states have supplemental programs that don't align with Federal requirements. Good luck sorting that out in the system.
Banning items on the same shelves as other items leads unscrupulous vendors to rename the banned items to let them through. Smaller convenience stores in ghetto neighborhoods are notorious for selling alcohol and cigarettes via EBT, programming their register systems to change the identity on the receipts. That pack of cigarettes is now "produce".
No it is because of the bottling companies lobbyists.
Coke is closing locations because of government cutbacks.
If EBT cards don't work that way, then why not?