The article mentions that retailers are generally willing to sell you a bulk lot of tickets as prizes for a contest/whatever and the some of them are also willing to refund you for any unscratched tickets left over.

There would be plenty of legitimate ways to get around it if you were determined. I obviously don't know the gambling laws for the US but from what I've heard about, some of them are pretty draconian and strange so maybe it is illegal to have a system at all.

The method the guy used is a simple one and does make sense as why it provides an indication of whether it is a winning ticket or not. The designers of the games didn't design it correctly to prevent this kind of information disclosure.