Yep, for whatever reason Ford delivered the Focus with lots of non-adjustable camber at all four corners. And yes again, the bulk of the problem is in the rear end. There's usually enough camber that even when combined with modest amounts of toe it becomes a recipe for eating tires. Camber bolts (along with a good alignment using very precise settings) are the cheapest (30.00 or less) and easiest way of making corrections.
In addition, Ford got hold of a batch of really crappy springs. These were delivered on early (pre 03) Foci. They were subject to sagging and outright failure (coils breaking from rust through). This problem continues to happen even after all these years. While I haven't heard of too many wagons experiencing the problem (they have a different and longer rear spring than sedans and hatchbacks) it could still be a possibility assuming they were sourced from the same place. Besides stock OE replacement springs, Bat Inc. carries several performance spring and shock options for the wagon that may interest you.