Who owns your stuff in the cloud?

Not being a lawyer I really do not understand one thing. Why on earth is it possible for law enforcement to issue a subpoena on a cloudprovider, regarding my data, giving them access, without my knowledge (worst case).

when the data resides on my home-drive, they would have to use a search warrant, I would know, I could go against this decision, appeal in a court.

Aren't they taking basic rights of me, if (worst case) I don't know anything of the subpoena and cannot this way appeal?

Isn't an example case needed, that makes it clear, that my data can only be accessed by law enforcement via a warrant, independent, where this data resides (cloud or home).