The 'crapification' of jobs is the direct result of the 'crapification' of the economy
The decline in the quality, pay and upward mobility of jobs is directly related to the dynamics of globalization, financialization, and the surplus of ordinary labor and capital.
Rents, taxes, healthcare, government fees, etc. all rise like clockwork; that leaves labor as the largest component that can be trimmed.
With the cost of capital at all-time lows, the pressure to replace costly labor with new software, robotics, etc. is intense. Software, robotics and related technologies are dropping in price even as their productivity increases.
Employees tend to overlook the overhead costs paid by employers: workers compensation insurance (soaring), healthcare insurance (soaring), disability insurance, unemployment insurance, 401K or pension contributions, etc.
Total compensation costs = wages + labor overhead. If labor overhead costs are climbing, the employer is paying more per employee even though the employees aren't getting a dime more in wages.
As system costs rise, those with stagnant incomes have less to spend. The share of income that is truly disposable is declining as the big-ticket expenses continue rising.
The net result of stagnating income for 90% of the households is stagnant sales.