They do that because it’s an incredibly insidious and craven way to gain power.
They spin economic news positive on the macro level to create the general impression that the economy is well. This lulls people who are doing ok into complacency.
They allow, and indeed play UP economic pain on the micro level because it makes people who aren’t doing well believe that they are being cheated out of taking part in the prosperity. The solution for which are Liberal progams for government intervention such as forced redistribution.