There's nothing inherent about scratch-off games that forces sellers to be in a privileged position about whether tickets they are selling are winners. If the buyer supplies a source of entropy that they commit to, the ticket has a it's own entropy.
Every such scheme is potentially flawed and subject to attack. I reference the McDonald's "Monopoly Game", that was subject to insider cheating for years before it was discovered. Scratch-off tickets are subject to similar attacks, as well as simple mathematical strategy attacks that transfer gambling advantages from naive players to well-informed players, skewing the published odds.
Yes, this is the way it works today but it isn't required by design. My reply illustrates how you can have a "scratch-off" game where the game provider doesn't know if the ticket is a winner when the ticket is printed.
If you have any ambitions for cracking a lottery game, go for the small games in states with unsophisticated gaming regulators.
In any case, playing scratch-offs successfully requires research into the rules, which players hardly ever do. For instance, if the top prize for a scratch-off game has already been won, you should never play that game again. If it hasn't been won, you aggressively sell those tickets to other people, let them scratch, and then collect their non-winners for the second-chance drawing. You can't rely on the odds on the back of the ticket, you have to continually recheck the prizes won and recalculate the odds, and only play when expected value rises above ticket cost.
And that ignores completely the possibility that convenience store clerks are cherry-picking all the winners off the spool before you get the chance to play. It's just not worth it for anyone, unless they cheat in some way.