It seems it is part of their business model to allow clients in developed countries to find people in developing countries (all with weak legal systems and corruption) to commit illegal acts (both violations of public and private law). Just look at how many jobs involve rewriting, scraping, penetration testing (really a guise for hacking others sites) modifying existing copyrighted content to circumvent laws.
Upwork as middleman profits -- and takes a blind eye to all this corruption - since cross border police investigations are so difficult to manage when dealing with corrupt countries.
In my case, I had my competitors procuring hackers off Upwork to take down my site. We found out because one person who was contacted on Upwork to bring my site down actually contacted me via my site and provided screenshots and other evidence. There was literally a job posted requesting contractors to take my site down.
We raised this with Upwork. They did nothing.
Guess what they said?
Their customer support asked if I had proof that my site had been hacked by the specific person who posted the job on Upwork and that if had suffered financial loss as a result of the hacking! It wasn't merely enough for their client to procure contractors on the platform to commit an illegal act. They wanted proof that I suffered financial loss!!
However, I can say that we are considering a civil suit against them. It would be interesting to see how this impacts their brand.
Note: Please forgive the messy and unstructured writing. I've been writing it while walking the streets of Central London shopping for X-mas gifts.