My maximum is zero percent. It's my money. If I am forced to be charitable, it's not really charity, is it? How much freedom would you be willing to give up for freedom? Your question makes no sense.
Here you show the extreme nature of your thinking and how detached you are from the real world in some kind of ideological attempt to have some fantasy society in which there is NO taxes...(or compelled charity), and in such a world, supposedly, necessary public services will still be carried out... ... OTHERWISE, we will truly be living in a survival of the fittest, dog eat dog world... Most people would NOT want to live in such a society.
Well, I might be wrong, but I think he's objecting to the idea of a mandatory contribution, not contribution itself. A free market for taxes, as it were. Once you put a number on it (say 30%, from the previous example) then suddenly you have a group of people looking to spend it. Government agencies, in today's society. They try to get all the money off the books every year, which means spending a lot of it figuring out what to do with the rest of it, and wasting a bunch more of it on shit that's not really wanted or needed by anyone.
Now imagine the opposite example, where there is no requirement, and everyone pays 0. Would they just sit around waiting for other people to build the infrastructure they want? That seems pretty miserable, obviously at a certain point, having clean water and electricity in your neighborhood becomes worth more than sitting in a hot dark room with your savings. You will spend that money, and there will be a person eager to provide those services at a competitive rate, because there is no central agency guaranteeing him the work, and his reputation really does matter for repeat business. The job gets done in the most efficient manner possible, as it didn't require a committee approval, or balancing it against other projects on the books, or waiting for votes, or some other bullshit that wastes everyone's time or money.
Now the reality is probably between those two things, but I wouldn't outright dismiss the idea of 0% taxes being feasible, or even better than what we currently have.