Except a lot of structs also derive and prefer `Copy` and a lot of rust code also avoids heap allocation which requires `Clone`. The `Copy` trait can be used implicitly like in the example here. On the other hand, due to the lack of garbage collector, you wouldn't be able to return the reference to the copy which might lead you to find your accidental copy.
I have yet to come on structs that implement `Copy` while being expensive to actually copy. The largest I can think of is `Uuid` from the `uuid` crate, which is 128 bits in size. This is a single word copy for most machines since modern hardware has 128 bit support for case like this. Still, two 64-bit words to copy is definitely negligible: that's equivalent of copying two pointers.
I agree with you for the garbage collector. By design, a GC allows you to willy-nilly copy without thinking about the consequences.