Not only can't they quantify them, but classical economics would argue that they are all intrinsically coupled via the market.
As an example of how these variables are all entangled, say that your job pays 150k a year - you spend 50% of your time on a high value task and 50% on a low value task. The company values these at 50k and 100k each. The work force grows due to some policy change or market conditions, etc. Wages fall ~10% but the business is expanding and a new junior worker is found to do the low value task. The company now pays them 90k to do this task fulltime while you are paid 180k to do the high value task fulltime.
In this case wages have been bid down, income has gone up, the work force is less skilled on average, and productivity has increased in aggregate, per-dollar, and per-worker (no task switching)!
I don't buy the increased productivity argument either, for the same reason we don't skew opportunity cost for doctors to come and scrub our restaurant toilet stalls.
However, I do agree if you convince people they are worthless... one can likely underpay them more easily. Note, $150k is already a low living standard in places like silicon valley. =3
You may be conflating income/productivity with living standard. $150k is a high salary - but cost of living can be even higher. Note that cost of living is primarily a euphemism for rent. So you may be working in a highly productive / useful field and earning a high salary, while your actual standard of living has reduced because you pay more for housing, land, your local restaurant pays higher rent and therefore charges you more for meals, ditto for all other services, etc. This is in fact what Adam Smith would predict as a natural consequence of population increase.
Maybe in a 3rd world country, but that is borderline poverty living in silicon valley.
I think my anecdote of importing doctors to get paid scrubbing toilets is a fairly solid augment against artificial income suppression in any field of practice. Adam would likely be horrified modern indentured servitude proponents still exist. =3
As an example of how these variables are all entangled, say that your job pays 150k a year - you spend 50% of your time on a high value task and 50% on a low value task. The company values these at 50k and 100k each. The work force grows due to some policy change or market conditions, etc. Wages fall ~10% but the business is expanding and a new junior worker is found to do the low value task. The company now pays them 90k to do this task fulltime while you are paid 180k to do the high value task fulltime.
In this case wages have been bid down, income has gone up, the work force is less skilled on average, and productivity has increased in aggregate, per-dollar, and per-worker (no task switching)!