"Also, to eliminate any confusion, grades 5 and 6 in Russia are roughly the equivalent of grades 7 and 8 in the US."
Where did you get that from? When I studied in Russia we'd skip grade 4 (don't ask me why!) and most students started 1st grade at the age of 7. Meaning grade 5 really corresponded to grade 4 in other countries.
Upon review it looks like it might only be shifted 1 older or possibly the same, but it's unclear. Russian education apparently starts a year later than in the US and, until the 90s(?), ended/still ends(?) a year earlier and, as you noted, didn't/still doesn't(?) include a 4th grade. The presentation from 2000 on Russian math education I linked to also states that "number 4 is usually omitted" and that the system "has been in the state of permanent reorganization." Thus, it's not entirely clear to me how the grades match up, so sentence excised.
For the past 10 years it's just about having the money to pay for your exams. Education has gone downhill since the collapse of the SU. Russia doesn't need mathematicians or physicists anymore. My uncle is a professor and gets paid well under $1K a month. All that matters is what the price of oil is, and how much they can export while the old refineries still haven't fallen apart. Russia's income is purely from oil & gas now.
Where did you get that from? When I studied in Russia we'd skip grade 4 (don't ask me why!) and most students started 1st grade at the age of 7. Meaning grade 5 really corresponded to grade 4 in other countries.