Most rigs don't receive large amounts of visitors either so the high cost and low volume of helicopter rides makes sense. A rig working as a rocket port needs t

Most rigs don't receive large amounts of visitors either so the high cost and low volume of helicopter rides makes sense. A rig working as a rocket port needs to move more people through it so the economics of figuring out a dock makes more sense. Also they have the tech with actively stabilized gangplanks to make the link between the more stable rig and the docks.