My guess is most hotel wifi access pages lack anti-automation (I've seen CAPTCHA on airplane wifi, but never hotel wifi) and there are enough Smiths/Lopezes/Kims/Lis out there that if you try each of those against every room number (100-1000) you could reasonably get free wifi in minutes. An optimization could include changing MAC address between each attempt to defeat rate limiting on the part of the access point.