I plan on sending one of my sets to get graded. By the time I receive it, send for grading (which the TPG will be bombarded with by then) and get it back it may well end up being close to 2022 by then.
It's the same reason they don't hire private companies to operate the mint facilities. Their goals are different. Private companies want profit. They typically work to improve efficiencies and customer service in order to increase profits. Departments of the government are not at all about profit, they about budget. Those who run the departments increase their power by increasing their budgets. The more inefficient a government department is, the more it costs to operate, the larger the budget has to be.