Why in the world would you allow listing of cars without the actual millage, millage is such an important critria, I would not waste my time to contact the seller, if millage not posted, and I would peter to use other websites where they mandate the millage such as Facebook Marketplace, Craig's list or Auto Trader than a site allows this.
We do collect vehicle mileage from all our sources, and I believe it’s displayed for the vast majority of vehicles. We’re a search engine that searches listings on many different sites, so we don’t directly control what information sellers provide. Could you provide some examples of vehicles that don’t have mileage listed so we can look into them?
Test this, try to list a car for sale on Marketplace, Auto Trader, or Craig's List , it is not possible to post the listing without entering the millage.
As a buyer, mileage is a major deciding factor, and when a seller hold off on the mileage listing, I know is most likely is too high.because mileage has the effect of the price of the car between 30-60% of the price.
you are providing the option to the seller to omit mileage that's not very good.