Because with Fakes you can basically provide delegates to act as implementation of the generated stub methods you can put any conditional logic inside that delegate.
In your case the following setup if equivalent with the moq example:
var stub = new StubIObject
{
Foo = (value) =>
{
if (value == 100)
// This covers the case (It.Is<int>(t => t == 100))
return value * 1.10;
return value; // This covers the default case (It.IsAny<T>)
}
};