I'm not arguing that services didn't exist.

I'm arguing that the Interstate Commerce clause was originally intended to apply to physical goods being transported across state lines.

You could transport physical money across state lines. You couldn't transport "a banking" across state lines.

You could transport horses, humans and machines. You couldn't transport "a labor."

Every one of these things comes down to some physical item that could be taxed as it crossed a border. That was the entire point of it.