See, when I originally said "It's not robbery, but if it was it wouldn't really count", that was me being a bit snide and unfair, but now it's a pretty fair summary of what you're saying.
The problem is, you're taking a narrowly legalistic view of this, and considering Amazon's actual practices, it's not even just "it doesn't count if it's illegal", but "it doesn't count if you don't get caught". Perhaps even "it doesn't count if, having been caught, you are not held to account". Guilt is constituted exclusively in being found guilty in a court of law. And when people say "Amazon are robbers", they are not very generally citing case law, but making a broader claim about the ethics of Amazon's business practices, and the place of such practices within civil society.