I don't think it's an issue of money, anyone running a mixing service or any other service should be able to afford a few thousand dollars a month for a good support team, the problem is the training itself, anyone who works as a support member in Whirlwind needs to understand it inside out, or else, their job would be a matter of relaying messages to an actual person who has the answers, and that won't help much.
A support employee is useless if he doesn't have access to actually solve problems, but an anonymous service can't just give such access to any "support employee". There's a lot of trust involved.
I just imagined when you visit Indeed or Glassdoor and see a job listed by Bitcoin mixer. By the way, I wouldn't be surprised if I saw that kind of job on Craiglist.
By the way, in this kind of business, I don't know how can someone risk and hire any 3rd party person. I think bitcoin mixer is a type of business that can only be done and managed by two or three childhood friends that somehow managed to become IT specialists & Web/software developers and managed to own tons of bitcoins.