The artist with over 67,000 uploaded their first image on the 9 of march 2015. So in roughly one year they have uploaded 67,000+ images.

I guess they're trying to catch up with SS.

But I still get rejects for things being too simple when other agencies accept them. Maybe there's a special deal for some people?

Just did a search too. Yes there must be something dodgy going on. A lot of those icons there's no way I would get through review. My rejects are much more complex than that, the sort of stylised illustration you could use as a logo.

I had a reject a few weeks back which surprised me. It could be an algorithm that picks out certain images and sends them to an inspector.

A guy who employs staff once told me that he gets half the pile of job applications and throws them in the trashcan because they are the unlucky half and he doesn't want unlucky people working at his company.

Many have complained about this in the Getty forums, but nothing is ever done.
It's very demoralising to search for one of your new uploads under best match only to find thousands of very simple and irrelevant (because of wrong keywords) images from a handful of serial spammers who are dominating and ruining the search results.
A few months back I complained about this to contributor relations only to be told that some of the names I put forward were already under investigation because other's had already reported them. And yet, several months on nothing has been done about it, the offending spam images are still up and running and the spammers are still uploading the same rubbish.
Remember some years back when some contributors were identified as inspectors by a special icon under their avatar? Well some of those inspectors, the same ones who used to give critique advice in the forums about rejected images being too simple, are now themselves spammers.
Something very dodgy going on.