In 2001, the U.S. passed a tax cut bill that immediately sent rebate checks out to most households. It produced a modest, short-lived bump in the economy but did not increase sustainable demand or create long-term growth. It certainly didn't prevent the recession after 9/11 or the financial meltdown.

Government-funded spending does spur economic activity--true. However it is merely temporary and is essentially borrowing money from the future to buy fake economic growth today--which is why governments reserve it for truly crisis situations like the ones you list above.