With the availability of the "Flag as inappropriate" button on all job postings, and the improvements to that tool, it is a lot easier now than it used to be, to report problematic jobs, including scams.
Is there a specific reason why you feel that it is difficult to report a scam?
Remember that reporting a scam is only about you helping out other Upwork freelancers. It is a noble thing to do. But that is separate from you yourself recognizing and avoiding scams. Which is even more important.