I suspect that the data you are enumerating is not typed - for example, a lot of things that were written in 1.1 only implement IEnumerable, and don't have a custom iterator (you don't actually need IEnumerable<T> to do typed iteration - and indeed you don't even need IEnumerable to use foreach; a lot of 1.1 typed wrote special enumerator types to avoid boxing/casting etc - lots of work). In many cases it would be a breaking change to fix them.
A trivial example here is PropertyDescriptorCollection:
var props = TypeDescriptor.GetProperties(obj);
foreach(PropertyDescriptor prop in props) {...} // fine
but actually, PropertDescriptorCollection's enumerator is just IEnumerator, so Current is object - and hence you'll always get object when you use var:
var props = TypeDescriptor.GetProperties(obj);
foreach(var prop in props) {...} // prop is "object"
Contrast this to the (equally 1.1) StringCollection; this has a custom enumerator (StringEnumerator); so if you used foreach with var, you'd get string (not object).
In anything 2.0 and above, it would be reasonable to expect better typing, for two reasons:
- generics (for the simple cases), making it possible to write strongly-typed collections sensibly
- iterator blocks (for the non-trivial cases), making it possible to write custom iterators without going insane
But even then there are still cases when you don't get the type you expect; you can either (and perhaps more clearly) specify the type manually, or use Cast<T>() / OfType<T>().