I live in MA and wish that this were true, but do you have data / evidence to support that it rarely happens? Also, I don't know if you have tried to get your $10, but it's not like the sign is always obvious and every time I've tried, it's not like the cashier says "oops" and gives you the thing for free - they call a manager, the manager argues with you, other customers complain about the checkout delay you've created... there's social pressure there so I can understand why customers would not do this even when they can.
I've done this many times, and it usually takes about 5min (which sounds short, but isn't really that short). There is social pressure, but it's even stronger on the store than it is on you as a customer.
If this happens you can file a consumer complaint with the attorney general's office... https://www.mass.gov/how-to/file-a-consumer-complaint
They do follow up with serial offenders.
> other customers complain about the checkout delay you've created
Other customers are complaining about the checkout delay the store created, so I'm not worried about what they think.