It is entirely up to the TD/Club putting on the tournament on how they want to charge the entry fee.
If it's 19+1 = $20 for example, then TD takes out $1 for each player when figuring out pay out and witholdings etc.
If it's 20+1 = $21 for example, same thing as above, only TD will need alot of change to handle all the $1 bills in change.
It's the same thing as a PDGA tournament, you pay $50 to enter the tournament. The TD takes out $2-3 for PDGA fees, then $10ish for players package, $2 for other fees and oh maybe $2 TD compensation etc. Using this example, $33-34 would go to pay out and $16-17 goes to fees and expenses.
Don't forget that a lot of the $ goes to DDGA expenses like sponsoring various tournaments, Nationals, postage, materials, website operation, and more. DDGA has been barely scraping by after so many years and we had to add a way to bring in more money to be able to provide more to the organizations nationwide more...
Again, the $1 fee is not a burden onto the player, it is onto the club putting on the tournament, and one fundraiser could cover all the fees easily.