ra you keep talking in the "as if" instead of the reality of the is dropping.
Incomes have dropped while prices have risen.
The government can't take money that isn't there, no matter if we have an income tax, a national sales tax, or a combination. If incomes drop significantly then tax revenues will drop. But that would be the least of our problems.
Your going to far to the other side of the point to make your point. I am not talking about total depression as you allude to at the end of your statement.
What I am talking about is the dependency of Gov on the incomes of the people. This helps to keep them somewhat honest with policy etc when it comes to our earning potential.
If they are going to do something that will affect our pocket books, it will affect theirs.
With a sales tax, who cares, they will get theirs no matter what. I don't care how little money someone has, that little bit will be spent and they will end up paying the tax, where as now they may not pay any tax at all.