I keep thinking the Amazon Echo and Google Home should be free because Amazon and Google are getting far more benefit from the devices than the purchasing consumers are. As it is, they're building Trojan horse devices for our living rooms *and* they're getting consumers to pay for them.
If the devices were free, however, I suspect fewer people would want them because they would have less perceived value. By charging a substantial price for them, Amazon and Google make consumers think they're getting something valuable while also making more money. Making them free would effectively be admitting what they really are.