Your assertion about intellectual property is inaccurate, libertarians only believe in intellectual property rights protected by contract, not government
I don't think anyone who calls themselves libertarian (edit: should have been 'anyone who is libertarian') could approve of any kind of government. Your argument about collectives taking a vote to justify actions applies just as readily to theft and extortion as it does to rape. That is essentially what every government does to its citizens by taxing them — a sufficient number of people have voted by proxy to take a certain amount of your property gains and use force in order to ensure that you comply.
There is a bigger problem with enforcing intellectual property rights by contract. It is easy to illustrate with a book. Let's say that a book has as its first page, the terms and conditions of sale which are, basically, standard copyright provisions. If the first buyer of the book loses the book, is the person who finds the abandoned property still bound by the terms and conditions of the sale? Perhaps, perhaps not. If the book becomes old and worn and some pages fall out, including the terms and conditions of sale, whoever finds the book can't be aware of the rights protected by this contract. Similarly, an unscrupulous person can violate the terms and conditions of sale, and all violations of the contract thereafter can only be attributed to that one unscrupulous person. Enforcing a copyright contract is simply untenable with physical objects. And with digital objects, assuming the absence of Digital Restrictions Management. It seems that free market forces would make most copyright-via-contract schemes unpopular.
I don't think anyone who calls themselves libertarian (edit: should have been 'anyone who is libertarian') could approve of any kind of government. Your argument about collectives taking a vote to justify actions applies just as readily to theft and extortion as it does to rape. That is essentially what every government does to its citizens by taxing them — a sufficient number of people have voted by proxy to take a certain amount of your property gains and use force in order to ensure that you comply.
There is a bigger problem with enforcing intellectual property rights by contract. It is easy to illustrate with a book. Let's say that a book has as its first page, the terms and conditions of sale which are, basically, standard copyright provisions. If the first buyer of the book loses the book, is the person who finds the abandoned property still bound by the terms and conditions of the sale? Perhaps, perhaps not. If the book becomes old and worn and some pages fall out, including the terms and conditions of sale, whoever finds the book can't be aware of the rights protected by this contract. Similarly, an unscrupulous person can violate the terms and conditions of sale, and all violations of the contract thereafter can only be attributed to that one unscrupulous person. Enforcing a copyright contract is simply untenable with physical objects. And with digital objects, assuming the absence of Digital Restrictions Management. It seems that free market forces would make most copyright-via-contract schemes unpopular.