Maxperson
Morkus from Orkus
The background is just that, though. Background. In a living world where events happen, it's just stuff the players hear. Often it will just be that the baker and his wife split up, or the Duke had a stroke and his son took over. It's not all world shattering events. And the players are not intended or expected to go investigate these things.The way I see it is the setting around them changes due to certain events happening, example a bunch of APs/modules are happening in the background and their unfolding stories could affect the direction and quests taken up by the PCs.
How many people run sandbox this way, I dunno - I do, so you may have a point if you believe it is more common for people to run static grid exploration play.
I tend to believe the setting is a major influence in sandbox - it is the GM stories (published or otherwise) and the GMs npcs with motives, rumours and gossip.
If they hear the duke had a sudden heart attack, they might go see if it was natural, or they might open up a shop to sell the wares they find while adventuring, or they might go investigate the Forest of Endless Boredom to see if it's as dull as its reputation indicates, or...
The players drive the game. If they are passive, literally nothing happens. They sit there and stare at the DM who stares back. The sandbox is over and the DM has to start putting in all kinds of hooks and set them on adventures, etc. Not a bad way to play, but that's not a sandbox. If they are proactive, they set their own goals and desires and start taking action to reach those goals and desires. The DM is entirely reactive to their declarations, even when the world around them is doing stuff.