Not sure your explanation is 100% — the system seems to me like it’s designed such that if every student put the same amount of time into each of their subjects then they should get the same mark (with a couple of minor, but usually irrelevant caveats).
So my assumption (and seemingly yours) that usually students taking standard put in less time than students taking advanced means that you don’t need to put in as much time into standard than advanced to get the same mark.
Either way, the system is secondary - the choice is really yours. If you need advanced for some course you may consider doing, then definitely keep it. Otherwise if you aren’t enjoying it and are struggling with it there’s no shame in doing standard - it’s a really underrated course in my opinion thats actually pretty decent for exposing you a variety of situations where you may need math (I don’t know btw, I don’t take it I can only tell you from my limited research) but if you’re going to hate math adv and you don’t need it, there’s no good reason to take it
The scaling for a subject is determined based on the performance of the cohort in english (or in the case of maths, a common scale is used, so it’s based on the common questions/subjects between courses). The overall effect of scaling is NOT that identical effort (assuming all else such as relative aptitude to the average person in the subject area is equal, which should be the case for maths given it’s one subject area) produces an identical aligned mark (ie the one you receive on results day), it is that an identical amount of effort should produce an identical scaled mark, which is used in the calculation of the ATAR. The flaw of taking maths standard is that in almost all cases (I’ve seen it happen over and over), students who drop to standard tend to put in less effort than they would in advanced, rather wasting the extra time (which it goes without saying will have a negative impact on atar) or spending the extra time on other subjects, which still has a negative impact, as given that maths is their weakest subject, the increase in scaled marks which is produced by an increase in effort in maths is much more significant. If a student’s ability in maths is poor and they wish to get a high ATAR then standard won’t increase their scaled mark, and the optimal decision (once again, purely from an ATAR perspective) would be to drop maths entirely. It is indisputable that dropping to maths standard is a poor decision purely from an ATAR perspective.
As I acknowledged in my original post, there are absolutely merits to taking standard if ATAR is not the primary consideration. For people entering non-STEM based fields in university, into the workforce or into a trade following high school, if ATAR is not super important for their future endeavours, then standard is absolutely a good choice. And as I said, there is no shame at all in doing standard.