It's only a choice if no one applies for turnips. If you got two people of comparable skill/experience applying and one is willing to work for free, who do you think is going to be hired? Turnips is even listed before cash.

People bring up other sites, but DV isn't like the usual tiny forum site where staff doesn't make a profit/living off the place and is lucky if they can cover server costs+new assets each month. If the DV owner thinks they should be able to make a living off the site, than they should treat their employees, even freelance ones with equal respect.