I am pretty sure that the majority of the "salaries" paid out have to do with reimbursement for travel expenses, with the exception of the salaried full time ABA employees.
The cities that have hotels large enough to accommodate the production that is the ABA oral exam are not cheap travel destinations. The hotels that are large enough are usually the $300 a night places. The number of examiners it takes to pull it off is quite large, and, although they are not paid, their expenses are taken care of, including travel and hotel.
In addition, the directors meet more often, and I feel certain that this is why they are listed as being reimbursed for $20K. Probably travel, hotel, and food costs. I am not thrilled with the costs associated with the process, but I don't think anyone is getting rich off the process and , in fact, most examiners give up a week of their vacation or CME time to do this.