Not every work is interesting enough to keep your employees motivated. For example, in the article they mention a company that resells beauty products. IMHO I can understand people not being incredibly motivated by this.
It shouldn’t be difficult to track the performance of the employee with metrics that are actually specific to the task they are hired to do (Number of listings/sales).
Taking screenshots, tracking keystrokes and mouse movement? It’s extreme, and doesn’t even relate to the work they’re doing in a direct way. You might be able to see them slacking off, but it doesn’t tell you the quality of the work.