With theft the originally owner loses what is stolen, with copyright infringement the owner only loses the license fee for 1 copy.
There used to be an anti-piracy lobby group in Australia literally called “Australian Federation Against Copyright Theft”. I always had an issue with their name since they were really against copyright infringement, not “copyright theft” which is just a nonsense term like you said. It’s been ruled several times by courts both in Australia and in the USA that it can’t be called “theft” (e.g. techdirt.com/…/surprise-mpaa-told-it-cant-use-ter…).