I find it odd how little a basic principle enters into this: don't do something to someone when they make it clear they don't want you to do it.
¹ in the sense of owned by the State, not listed on the stock market
As for the commonality of principles, game theory explains most of them, so it isn't more surprising than that we all work with the same prime numbers, say. A simple principle of reciprocity will produce something along the lines of "respect other people's wishes".
I can't say I agree. I mean, a serious, interesting essay can certainly be written on the ethics of scraping. But these short preludes on technical posts just end up sounding either like a disingenuous legal disclaimer or a preachy paternalistic tirade.