The $2,500 is maximum fine, been on the books since 1990 I think.
$25,000 fine if a shop removes Cat and doesn't replace it.

Likely hood of getting fined is remote....but it ain't 0, lol

Used Cats from wrecking yards usually aren't to expensive.

I think shops are required to report vehicles without Cats as well, even taking truck in for an alignment could put you in a place where you wouldn't want to be.
And the shops look for this type of thing because they want the money to replace cat, use the old "vehicle safety/road worthiness" thing, problem is the Law is on their side in this.
Just as a heads up