Florida Federal Withholding Tax

My friend lives in Florida and her company didn't take any of  her federal income withholding tax because she made less than $10,000.00 for the year of 2020.  My question is the paper they give her was from SmartAsset online website. The paper show the household income the location is where she works at and her filing Status which is (Married). How can the state of Florida have different Federal income withholding tax rules or is this a general rule from the IRS for every state? I know that their household income is above $10,000.00. 

I need to get back to her soon before they file their 2020 Income Taxes so they can file correctly.