This is a general problem. These things worked before those platforms became successful enough to warrant a cottage industry around them. Nowadays there are "reputation management" companies specializing in getting bad reviews deleted by any means and shady businesses will actively bribe or shame customers into giving them perfect scores. For a while everyone knew that 5 star and 1 star ratings are often fake and that you should check the ratings in between to get the real ones but nowadays those often don't exist or are just as fake (often left by shadier "reputation management" companies to score them an easy win if the business hires them).
What services like Airbnb would need would be direct partners actually testing the listings in person. But that costs money and requires hiring staff, which is antithetical to the business model of "gig economy" apps which exist in order to avoid the overhead of running a real company in that industry by instead offloading all the work to "gig workers" as independent contractors.
What services like Airbnb would need would be direct partners actually testing the listings in person. But that costs money and requires hiring staff, which is antithetical to the business model of "gig economy" apps which exist in order to avoid the overhead of running a real company in that industry by instead offloading all the work to "gig workers" as independent contractors.