All types default to be copyable, that’s automatic default for the Swift, since they are fine for majority use-cases. Non-copyable types is mostly can be seen as on-demand optimization technique where you don’t want to allow copies for some reason or that’s a generic wide-purpose library code.
If you don’t see how it can be applied in your code, great chances that you don’t need it (oh, @sliemeobn actually has already stated that, huh). Otherwise it would be clear what behavior you’d like to enforce on the type in your use case.
You see it in standard library definitions because they have to work in a large amount of cases without restricting usage. Like Optional type being generic over both copyable and non-copyable types, since it is just a wrapper around some user type.