Thats actually why I argue objectivism as being aligning better with what's possible within the field of ethics. The whole idea is you can only morally do what you want, without intentially removing others freedom, unless they pose a direct threat to your freedom. As a rule of thumb, this actually works exceptionally well.
Murder for example is wrong (morally), by that code of conduct. Traffic laws would be moral because it keeps others from removing your freedom by either not letting you access the road or accidentally killing you by being reckless. It also handles the Hitler argument, whereas some utilitarians my argue what Hitler did was moral.
The whole point of this philosophy is to maximize personal happiness, while minimizing conflict. Data has little to do with it, because respecting one another is the whole point. When you start discussing ethics in terms of "sociatial good" it starts requiring one to know the future. For this reason, I'd argue objectivism, when applied, provides the more useful form of ethics, where one only has to worry about their own happiness, while not intruding (too much), on others.
Another problem is whether it's OK to require a thirsty person in a desert to give up all their assets in exchange for water, and whether it's OK for the thirsty person to knock you out and take the water in response; most people would side with the thirsty guy for what I think are very good reasons in terms of the practical implications while objectivists would not.
To your other problem, I fully understand the practical implications. Knocking the guy out and stealing his water is pretty unethical. However, coming to equitable terms is fairly easy. More humans can think one step ahead and just gouging the guy for all his posetions means he won't help you in the future. Long term, that is bad for you, thus you'll likely not charge too outrageous
For instance, why is making noises infringing on your freedom from noise, but the requirement of silence is not an infringement on your freedom to make noises? Freedom from noise and freedom to make noises are both "freedoms" and one comes at the expense of the other. What is the way to weigh their relative importance which is universally applicable to other cases and not rooted in culture or personal preference?
"He excludes from the scope of ethical obligation not just the literally impossible, but also anything that is merely beyond the abilities of the normal person. Ethics cannot tell us to do what would require the impartiality of saints or the foresight of seers."
Superman is not ethically required to save the world from the giant meteor because the average man could not. I, as a professional programmer, am not required to make ethical choices when writing software because the average person cannot write code at all.
It's is as if the claim is someone shouldn't avoid doing harm that their above average abilities offer them?
The authors seems to be saying something dissimilar to that: people should't not be require to do more than average person, even if they have the capability to do so.
Programmers shouldn't be required to perform code for charity for their friends and family. Doctors shouldn't be required to save lifes.
Ultimately, the TLS didn't even claim a viewpoint. They merely presented a variety of opinions and critiqued them.
Maybe each Individual is capable of being just as good as they are capable to be bad. Would that even the score and make the problem disappear?
Then rises the question of "how do I not get fucked over in life?" as well. So it gets confusing.
Where to even beging, is good universal? Do the criteria that make "a good being" good constant, or does it mutate over time?
I there a single, or even multiple non-contradicting, right answer to this question? What is good?.
If ethics is dependent on knowledge does that mean Aztec human sacrifices were a morally great deed when performed by the Aztecs under a misconception that the souls were going to heaven? What about Hitler's genocide under the misconceived belief that he was creating a better and more peaceful Europe?