When many racetracks first opened as new tracks with slots, the same scenario was in play. I am speaking of Thoroughbred tracks. They still had the same horsemen and horse population with a barn full of $5k claimers. So they wrote races and conditions from the available horse population. $5K claimers up to say $20K.
Guys were taking $20 claimers and dropping in for a $5K tag. With the purse being $30K the risk was minimal.
Allowance races offered a lucrative safe haven as their purse went from $9K to $40K. Finishing 2nd and keeping your conditions was the game.
Presque Isle Downs was a perfect example of this. Of course things have changed but, it was wild for a while.