I agree with you.
Let's imagine an academic physician who is full time clinical. I have never seen an academic job that didn't at least on paper have a non-clinical day. So they're immediately 0.8 FTE. But what do all academic people complain about? Their academic day isn't protected or they spend the day catching up contours and notes. I know a number of people in private who have a similar arrangement with no scheduled patients on one day, though they may see add ons, do other admin tasks, provide coverage, etc on that day.
So MGMA median is ~9000. There is nothing to normalize for private practice. That's just a median full-time rad onc. If you divide that by 0.8, you get approximately the FPSC median of 11,250. So there's your academic equivalent full-time clinical rad onc. Indeed, the FPSC presentation I linked earlier has an average clinical effort of 0.73 FTE.
But you're right here--if the thresholds for salaries, bonuses, etc are set to 11,000+ wRVUs based on FPSC medians, that's setting an unrealistic target. Full-time clinical has to be more like 0.8 x FPSC to be more in line with MGMA/AGMA and salaries/bonuses adjusted according to other effort.
Sure enough, when I was 0.7 FTE my RVUs were about 9,000 per year. I knew something was off because I was pretty busy, seeing the same number of consults as my private practice buddies, despite being told I had "1.5 days academic time". It's all a matter of understanding (and fudging) the numbers.