It's probably worse for the environment to ship the glass, fossil fuel use, than it is to make virgin glass. Glass is made from sand which is pretty easy to find, it's also cheap to buy. To recycle glass it needs to be ground down and reformed, a process as laborious as using sand. In a landfill it's stable and non toxic, not really an environmental issue. How stuff is recycled is interesting, it's worth investigating.
Polystyrene foam packaging also has the same problem. It can be recycled except it's expensive to transport as its 90% air. My depot doesn't accept it only because of its size/weight ratio. It could be used to make new products but it would cause more environmental harm than benefit in my cities case.