No.
For one organizer I’ve done events with JTP in the K-3 section and tournament memberships in the K-5 and open sections. I will grant that the open sections are generally 80% or more of K-12 players, but rarely are such events completely scholastic.
I’ll also grant that the K-3 section is generally about half the tournament and the K-5 section is generally more than a third, leaving less than a sixth for the open section with about 3% of the entire tournament being adults.
I’ve not asked for any donations, but I don’t suppose I’d turn them down.
I’m planning this at the Chess Club and Scholastic Center of St. Louis, tentatively for July 2nd. (with another event on July 3rd, also free, likely)
There will be some sort of prizes – trophies, lessons, memberships or discounts are possible, and maybe free entry in a future event – but cash prizes aren’t planned.