Libertarians don’t have a problem with common defense. Maybe don’t straw man positions? Try Mises.org or Rothbard if you want to steelman a different point of view.
Discussion
The issue is with the use of coercion and violence to accomplish ends. People would be more than happy to pay for their communities to be protected by trained and armed individuals. And members can donate to those that can’t afford the service. The idea that society would fall apart if we didn’t have a government that took people’s money by force is a psyop to get people conditioned to give more of their money to the state. Income and many other forms of taxes were not always a thing in the US.
You just described a state with common protections and common welfare... it's almost as if humans through the entire agrarian age have invented the same thing over, and over, and over again because the citizens find value in it. But, as with all organizations, states become lazy and corrupt, and end up being the predator it's citizens feared all along.
The protection and welfare is provided voluntarily, which is a key distinction. I’m not suggesting an overnight abolishment of taxes. Doing so would be like quitting heroin cold turkey, which would likely be fatal. We can rationalize why we need to have a group in society that has a monopoly on violence and coercion which won’t let individuals opt out without risking loosing their freedom.
We can rationalize lots of things.
It's almost as if; if you are residing in a territory with a pre-established common defense "a state" you are consuming the products of that state ( peace, law enforcement, jails, court systems, enforcement of property rights) The taxes the state forces you to pay uphold that system... if the state didn't force everyone to pay the commons defense would collapse due to the tragedy of the commons and the free-rider problem. It sucks to pay taxes... it sucks waaaayyyyyy harder to live in a lawless society without private property
the degree to which you can say private property is protected varies pretty widely and this redistribution of coercively collected, and often legally grey taxation has reached a level in most places now where it's hard to say that private property is being respected at all anymore.
most of europe is sliding fast down the hole into communism via progressive increases in taxation and regulation.
I agree, it's a dirty slimely compromise... it's like the old saying: What's the difference between protection and extortion? The price.
Willingness to participate.
rationalising also, the whole "price of civilised society" hooey, when there's nothing civilised about coercion and extortion.
That is the crux... the Hobbs idea of the consent of the governed being false: we are born and coerced into these systems. I think the Amish hold the key to making the Hobbs idea true: Rumspringa. I think when a child turns 18 they are kicked out of society for a period of time and to return they must sign a literal social contract. Also you can sue the government for damages based upon the contract.