In the United States, you are to file and pay taxes.
The only thing that’s voluntary about it is that you are the one that gets to do it, instead of the government doing it for you.
Because of that, you can choose to use various legal tax exemptions to your advantage to pay lower taxes. If the government was calculating your taxes for you, there would be a known way for the government to know what you should pay.
For instance, say you owned a legitimate part-time business on the side in addition to a regular job. You may be able to claim certain tax exemptions for that business according to the tax law.
Common and legitimate business expenses might be your car, mileage, equipment purchases, or a separate home office. I can’t help you write off these legitimate expenses.
It’s voluntary for you to own this business, but you are responsible for filing taxes for this business.