The worst part is how big of a pain it is to even sign up. On some flights, it takes my United account and will automatically charge my CC on file. Other flights, I need to enter in my name, address, CC details etc. On shorter flights, they are losing out on revenue because I simply can't be bothered to wait till we are over 10,000 feet... fill all those fields on my tiny phone keyboard, then have a 50% chance the wifi will actually work for the remaining 40 min we are over 10,000 feet.
They need to settle for one sign-in paradigm and that paradigm had better include rapid sign-in capabilities.