For anyone who isn’t interested in reading meandering articles:

They’re using smart phones placed on the table and sitting in specific position to the dealer while wearing ear buds.

The solution is no phones on the table. Which is already a rule in some casinos.

No ear buds is also obvious but could be a violation of the disability act in America if the player has hearing issues.

It’s less clear, since the article doesn’t mention it, if there is a way to train dealers so the cards cannot be read as they are dealt. It’s been a while since I’ve played but I feel like with blackjack, the cards were slide from the card shuffler directly to the player, leaving no opportunity for a player’s camera to read the face down cards.