It seems to me that, putting it simply, we have things we (as a society) want to do and how much we (as a society) are prepared to pay for it. So the minimum income (I'm avoiding "taxation" for now) is the cost of what we have decided to do. Lower income results in debt. Higher income is ... unusual.
A can't see what is gained from alternative (to taxation) means of income, other than to confuse the issue. No matter how you do it, paying for public services means taking money away from people. You can shift the load around, but it still isn't free. In the case where there are natural resources that can be applied to income, which is about as far from taxation as you can get, we are still taking a common source of wealth and appropriating it to pay for what we have created.