It is because you are earning so little.
If you file your own taxes (not as a dependent), you get a $12,400 standard deduction for your 2020 taxes (filed early 2021).
That means you pay $0 in federal taxes for the first $12,400 in earnings.
At 8 hours per week, that equals 416 hours per year. (8 * 52 weeks).
If you make $15 per hour, you earn $6,240 per year. (416 hours * $15 per hour)
If that is all you make, you will have no federal taxes liability. Anything you paid in federal taxes would be refunded when you file next year.
Now, if Target is a second job. Find out how much you will earn at your main job. Go to the tax tables and find out what tax bracket you are in. Then have Target take out that percentage from your earnings.
The Internal Revenue Service (IRS) has announced the annual inflation adjustments for the year 2020, including tax rate schedules, tax tables and cost-of-living adjustments.
www.forbes.com
For example, if your main job pays $50,000 and you are single:
12,400 is tax free by standard deduction
9,875 is taxed at 10%
27,725 is taxed at 12%
Have them take 12% out.