Ah, I see the confusion. Wireless in the context of radios means you don't need a wire to carry the source signal. As in the radios a hundred years ago that received broadcasts wirelessly from radio stations, unlike telegraphy that needed a wire to carry the message, but wireless still needed mains power by wiring the radios to the mains sockets.
The same terminology has been carried forward and wireless only means no wires to carry music signals. So technically a wireless speaker may still need wires for mains power; but a layman would be entitled to ask the question you are posing, and in that sense, these are not wireless speakers.