It is a valid question to wonder about the practicalities of Volunteerism. Would it become every man for themselves? Absolutely not. People would voluntary come together as social units under rules / laws for which one truly “chooses” to reside where the cost for exit is relatively small. Marriage, having children, Religion, employment, professional organizations, opening a business, etc. are one of many areas for which we voluntarily exchange our individual freedoms for benefits we perceive as being greater than the freedoms sacrificed.
One measurement toward how much you truly “choose” to transact with another individual is the level that you can simply “opt out,” say “no,” or move away.
The Founding Fathers had the concept right to provide for States to give more “choices” to its citizens. It’s unfortunate that the 10th Amendment has been disregarded causing the monopoly we call the Federal Government. Luckily we’re seeing more instances of State Nullification, a trend for which I hope occurs more often. The Free State Project provides a beacon of hope for New Hampshire and Act 20 / 22 to pay only 4% tax in Puerto Rico are other great options now available.