The trouble is that interest rates are a blunt instrument. They work on the economy only after a long lag which may be six months to a year or more. The same is true of income tax cuts. They leave more money in consumers' pockets only after months of delay. A cut in income tax rates now, for example, wouldn't affect the take-home pay of many taxpayers until next year when they get tax refunds.
Governments are reluctant to make such cuts because of the danger of mistiming.
The cut may have its effect in a future time when it isn't needed. Or if people are still afraid of losing their jobs, they may sock the money away rather than spending it.