Very interesting, yes. There’s an underlying assumption to all of this that the student won’t be using the same contractor consistently.

There are also contractors out there who can model the writing style of someone else. I doubt that they’re common in the price range that student essays go for, but those people do exist. Whether these people can accurately model the writing style is still open to question, but I imagine that universities will be wanting very clear cut evidence of differences in writing styles before they take an academic misconduct case forward.