I can't say I've installed any sort of doorbell for a very long time! Are you saying that they are now all battery-powered? Even if 'wireless', they must get their power from somewhere, even if the bell push(es) communicate with 'the bell' wirelessly.Yup, another viable option. Although I have literally never installed a wired doorbell. Ripped out a fair few, repaired some. But never installed one. I don't know what sales figures are actually like, but I suspect they're not long for this world.
Kind Regards, John