The extremely high efficiency techs are there to keep factories (somewhat) profitable when trashing large proportions of their output (and possibly significant proportions of their inputs as well). Which is something of a chicken and egg situation, since the high proportion of trashing is due to over-production by factories.
I don't think there is a shortfall in demand for RGO outputs (at least not ones that are factory inputs), because the number of factories increases so much. Also, the proportion of pops in various jobs depends a lot on whether China industrialises. But in any case, the proportion of buying power does shift away from RGO's as well.
Ultimately, money is always increasing in the game (due to gold creation from mines) and so is population. Part of the late game economic problem is that unequal income distribution relative to demand can easily result in money ending up effectively sterilised in bank accounts. Unless a government starts running a large deficit to borrow and recirculate this money, it reduces the effective money supply. Hence pops lack actual income to realise their demand for goods and the market exhibits high prices (due to high desired demand) and low sold volumes (due to low effective demand). High prices help keep prices down (and pop poor) and encourage over-production; while low sold volumes keep factories trashing large volumes of product.
A system that worked properly would need:
1) factory production levels that respond to effective demand (not phantom demand), so avoiding trashing output and creating massive overproduction
2) prices that relate to effective demand, not phantom demand, but also respond to excess production capacity (lower prices when much more could have been produced)
3) pops to buy life needs and possibly everyday needs ahead of factories, though perhaps not luxury needs (allocation to pops would need to reflect effective demand in all categories)
4) base profitablility of RGOs and factories adjusted so that outcome reasonably balanced
5) factories capturing market share from artisans by pushing down output prices (and potentially also expanding demand).
I don't think there is a shortfall in demand for RGO outputs (at least not ones that are factory inputs), because the number of factories increases so much. Also, the proportion of pops in various jobs depends a lot on whether China industrialises. But in any case, the proportion of buying power does shift away from RGO's as well.
Ultimately, money is always increasing in the game (due to gold creation from mines) and so is population. Part of the late game economic problem is that unequal income distribution relative to demand can easily result in money ending up effectively sterilised in bank accounts. Unless a government starts running a large deficit to borrow and recirculate this money, it reduces the effective money supply. Hence pops lack actual income to realise their demand for goods and the market exhibits high prices (due to high desired demand) and low sold volumes (due to low effective demand). High prices help keep prices down (and pop poor) and encourage over-production; while low sold volumes keep factories trashing large volumes of product.
A system that worked properly would need:
1) factory production levels that respond to effective demand (not phantom demand), so avoiding trashing output and creating massive overproduction
2) prices that relate to effective demand, not phantom demand, but also respond to excess production capacity (lower prices when much more could have been produced)
3) pops to buy life needs and possibly everyday needs ahead of factories, though perhaps not luxury needs (allocation to pops would need to reflect effective demand in all categories)
4) base profitablility of RGOs and factories adjusted so that outcome reasonably balanced
5) factories capturing market share from artisans by pushing down output prices (and potentially also expanding demand).