Upon consideration, it seems to me that "compulsory attendance of the voting booth", while probably not literally inspired by actual sadism, is perverse to the point of being indistinguishable from sadism.

Avoid inflationary use of terms. "Sadistic" does not mean "a policy that I disapprove of". Being unable to distinguish the two is a failure of your own comprehension, nothing more.

If a country gets "inadequate voting outcomes" (what does that mean, exactly?)

That means that the writer refrained from prescribing preferences to outcomes or making any claims about the merit of any particular election and left it to the readers judgement. Some examples of things that could be inadequate would include too few people voting, if the selection bias of only aggregating the preferences of people who have nothing better to do at the time than voting rather than the preferences of everyone resulted in inferior candidates or if the psychological impact of the practice is somehow sub-par.

However, the more relevant-to-the-conversation response is that "society's" interests in this case are far too diffuse and theoretical to serve as any kind of relevant analogue to the case of "one very specific person (i.e. Bob) doesn't want unpleasant experiences inflicted upon him". That's what makes it a poor analogy.

You are proposing a general cultural rule for how people must behave (don't introduce yourself to strangers on planes) for the benefit of Bob. This amounts to a large cost in lost opportunity and freedom that is paid by the people you consider "too diffuse and theoretical" to deserve consideration to suit the convenience of Bob who is important enough for you to make up a name for him. All the other people who have Bob's particular psychological disorder presumably warrant your consideration despite being diffuse and theoretical.

(And by 'psychological disorder' I refer to whatever condition results in Bob taking damage equivalent to the physical and psychological damage most people take from being punched in the face.)

Non-compulsory voting has the disadvantage that certain people will refrain from voting just because of the inconvenience of going to the voting booth and others won't, which may bias the result of the election if the extent to which voting would be inconvenient correlates with political positions for whatever reasons.

The idea that "society" has rights, or that "society" can be benefited or harmed, independently from the good or harm to any individuals, is one of the most destructive ideas in human history.

Sure, savageorange could have found a telephone book and tried listing everyone individually. But saying 'society' seems more efficient. It refers tot he case where many unnamed but clearly existing individuals who need not or can not be named would be harmed.