Why is it customary to say that a hypothesis has "not been rejected" rather than "accepted"?

It is customary to say that a hypothesis has​ "not been​ rejected" rather than​ "accepted" an because we cannot state that the null hypothesis is true, only that is has not been rejected. Also, it not possible to prove that a hypothesis is true; it is only possible to prove that it is not false

Fiscal policy because it refers to the use of government spending and tax policies to influence macroeconomic conditions, including aggregate demand, employment, inflation, and economic growth.