They are part of the reality surrounding us. It takes us many years of learning and experiences to make a difference between real and fake service offers, and there is no bulletproof method for identifying all the scammers.
The fake job offers are even more complicated, because they can appear in multiple contexts. Two formulas I've read recently on LinkedIn are about keeping a list of vacancies in order to polish the company's image in front of the shareholders, and respectively to have a pool of candidates in case a specialist leaves the organization unexpectedly.
The games of the corporate world might affect the freelance job listings as well. Ultimately the companies backing those listings have a market share, a reputation, and more often than not they have a stock market quotation. In other words they have to demonstrate stability in their activity and income flows despite of the impacts of the technology, economics, and geopolitics on the job market.
The daily count of new offers on a concrete job listing is publicly obtainable, but the daily count of contracts actually concluded and their values are trade secrets. About 10-15 years ago the market of freelancer platforms was not yet saturated, and it was possible to grow such a business despite of committing errors in a row.
At present specialized job marketplaces are concurring for a reduced number of buyers (project owners), and a suddenly increased number of sellers (workers hired during the epidemy and then fired). In my opinion some of these platforms will probably be sold, and until that we cannot expect major changes in their policies.
The fact is that a freelancer looking systematically for projects needs to get trained for filtering out a huge volume of suspicious offers and increasingly sophisticated fraud schemes.
When being between two bigger projects I'm taking up smaller ones, and over the years I've learned to avoid several types of offers, but following carefully selected conversations on social media is priceless, it keeps me informed about the newest tricks exploiting the flaws of this or that platform.
