Not that it doesn't turn the GPS off, rather that having it on doesn't necessarily mean it's using any power. It's only used when actively searching for a GPS signal so if you have no active apps with access to location then it's not draining the power either way. One clue this is the case is that the time it takes to get a position fix is much longer when it's not been used for the last few hours or miles.
Of course, access to WiFi information requires permission for accurate location now, as knowing which network you're connected to can give a very string clue as to location, and many apps seem to want that permission. Just because an app doesn't use the GPS doesn't mean it doesn't have the permission, so it can be hard to tell what is doing what.
All that said, my GPS is on 24/7 and I have an app that actively tracks my location but my battery easily gets through a day from an 80% start, so I think the battery argument is far less compelling on a modern handset than it used to be.