I think about this every single time I drive by a stretch of road that has these. You can't have public goods when the value of those goods in private hands is greater than the risk of, ahrm, converting those public goods into private goods.
When a society fails to provide sufficient opportunity for all its members then those who have been left behind can simply make up the difference by retrieving their share of the common wealth by other means.
The cost of trying to police this (ignoring entirely the moral and ethical implications of such policing) at the scale of e.g. all roads with guardrails is more than the value if replacing the rails, and likely substantially more than just providing the missing opportunity and removing the sources of wealth inequality that make wealth redistribution in the form of guard rails an inevitability.
But the police are paid for with the taxation of normal people, not the ultra wealthy class. Which is who would need to be taxed to redistribute wealth and opportunity. Our politicians have zero interest in properly taxing themselves and their friends. So easier to just keep taxing the middle and over funding policing.
When a society fails to provide sufficient opportunity for all its members then those who have been left behind can simply make up the difference by retrieving their share of the common wealth by other means.
The cost of trying to police this (ignoring entirely the moral and ethical implications of such policing) at the scale of e.g. all roads with guardrails is more than the value if replacing the rails, and likely substantially more than just providing the missing opportunity and removing the sources of wealth inequality that make wealth redistribution in the form of guard rails an inevitability.