Because the law was a special case for fax machines essentially instead of a generic one and they didn't understand the then very esoteric mathematical concept of converting arbitrary inputs to data and sending it in arbitrary ways.
We don't see laws today for unimagined hypotheticals like if governments if carrying a box with a stable frame of reference anchored wormhole inside that leads to a remote island with 1 ton of heroin is drug smuggling or not.
That's the law being broken. Not the tech.