It's not because they're collection classes, it's because they're interfaces. Foo doesn't implement them, but subclasses of it could. So it's not a compile-time error, since those methods may be valid for subclasses. At runtime, if this isn't of a class that implements those interfaces, naturally it's a runtime error.
If you change List to ArrayList, you'll get a compiler-time error for that, too, since a Foo subclass could implement List, but can't extend ArrayList (since Foo doesn't). Similarly, if you make Foo final, the compiler will give you an error for your interface casts because it knows they can never be true (since Foo can't have subclasses, and doesn't implement those interfaces).
