so the role of government is quite different in the two cases: it creates 'intellectual property', in the sense of 'what the owner is deprived of by so-called ip theft', while physical property exists in its own right
if we instead consider 'intellectual property' in the sense of 'literature, knowledge, or designs,' which the owner is not deprived of by 'ip theft', the role of the government becomes precisely opposite to its role with respect to physical property
taking a car as a paradigmatic example of physical property, private ownership rights (whether protected by the state, by moral suasion, by mob violence, or by any other means) protect your car from being stolen so that you can use it; without any security of ownership, people would just get in the nearest car and drive off. you could never be sure a car would be available for you to use, and this would eliminate any private incentive to build cars or to repair or maintain them, resulting in rapid material impoverishment; soon you would have no cars except perhaps for taxpayer-funded public transit. so private ownership rights serve to enable access to cars and similar material goods
literature, knowledge, and designs do not need to be repaired and maintained, especially now that we can use bittorrent instead of linotypes to reproduce them, and if someone else gets in my novel and drives off with it, why, i can still read it as easily as before. the involvement of the state in this case only serves to endanger access to literature, knowledge, and designs—precisely the opposite of the case with physical property
ultimately, intellectual property is completely incompatible with the security of physical property: the trade-secret code of your car's ecu deprives you of some degree of security in your use of that car
people do sometimes argue that an analogous situation obtains with respect to literature, knowledge, and designs: intellectual enclosure through so-called 'intellectual property law' enables creators to require payment from consumers, creating an incentive to write literature, discover knowledge, and create designs. perhaps there is some truth to this, but that is not the only incentive, and evidently it is not a necessary one, given that academic authors (who discover most fundamental knowledge) generally do not receive royalties, and free software reliably leads the software industry in innovation, having almost entirely displaced proprietary software as the basis of the world information infrastructure over the last 30 years