They don't have a clue or they just don't care is the answer most sharps already know.
What I don't understand is how come someone doesn't have a parlay card or bets designed to bring bettors back to the property. Football contests help, but what about the people who don't play them, and the 280 or so other days in the year, and what about getting people to the window to bet cash.
I'd offer a parlay card where if you won 1, 2, 3 or even 0 legs of a parlay card, you can cash a portion of your ticket back in for something.
The book can even change the odds or rules slightly where it doesn't even have to cost them any money in the short-term if they need to wear belts and suspenders to get the bean-counters to come on board.
You can even cash in a -110 bet for 1% credit on the next bet you make if you lose. Say, if you bet $110 to win a $100 and lose, you can get $1.10 discount on your next bet.
I'd think guaranteeing your clientele to come back onto your property to cash a ticket, even for a small amount has got to have value. Point is, you get them on the property. They must know profit-per-visit numbers, plus it doesn't even require additional advertising after the player has bought the ticket. I would think they would advertise to let people know, of course.
