Coming to Japan, military families have weight restrictions placed on our household goods shipments. Granted most people who move to a foreign country aren't able to bring even a 1/4 of their belongings, so we're fortunate in that regard, but the restrictions mean we have to be selective about what we pack out. Combine that with the fact that you don't know what kind of housing you'll get on base, if you even get to live on base (tower apartments have no yards) and the majority of people choose to leave most of their outdoor items, i.e. grills, lawnmowers, patio furniture, behind when coming here.
Summer is peak PCS season, so there are lots of families leaving Yokota. The moving companies are really strict about packing and shipping outdoor items; anything you want to pack out has to be immaculate, a difficult thing to achieve for stuff that has been laying around the yard for 3 - 4 years. As a result, people usually "junk" the majority of their outdoor stuff when the PCS from here. On base we have a recycling service that picks up anything and everything that you leave on the curb, from cinder blocks to couches, so this is typically what people do with their outdoor junk when it's time to go. However, those of us who are new to Yokota are usually all too happy to grab that "junk" off the curb. So far we've picked up a set of patio furniture with an outdoor fireplace, a propane grill, a lawnmower, and now.........a trampoline!
(A family in the building behind us is leaving next week, I've got my eye on their canopy porch swing!)