How exactly is the mobile web biased towards iOS? I've rarely (if ever) had to use a vendor prefix when developing for mobile. I am using Bootstrap, so maybe they're doing those for me.
Because some websites use user agents to determine whether or not to serve a website optimized towards modern mobile devices, and some of those user agent sniffers are only looking for Mobile Safari. If you aren't Mobile Safari or claiming to be, you either get the desktop site or the ancient mobile site designed for feature phones.