You are right that these companies don't pay the "actual costs" on environmental damage, but that's a separate issue, and not really relevant to the initial claim. If you claim that someone is using 7 kWh or electricity, you had better be prepared to show they actually do. (Besides, consumers don't pay for the environmental cost of building and shipping an SSD from Taiwan, either.)

Companies like Amazon may not care about environment, but they care a lot about saving money, and modern computers can handle a surprising amount of connections simultaneously: it's not like those beefy AWS instances are serving just your music.