Theory is always easier than practice. The principles of Thomas Paine's Common Sense evolved over time to become some of the components used in the US Constitution, but they're clearly different documents. Governments as they are today are the result of centuries of growth and change, and there is no way to fix what we have without a complete overhaul. Governments have NEVER existed to protect property rights. No nation-state was ever formed solely to protect property rights or individual liberty, as Rand envisioned. Instead, states typically served a mix of elite interests, collective security, economic needs, and cultural identity. Even when invoking rights, governments often subordinated them to pragmatic or collective goals—e.g., eminent domain, taxation, or war mobilization.
Rand's perspective was her own, but it had nothing to do with reality, it was an attempt to change the reality she saw. I can't idealize things in an academic construct and claim that 'this is how things should be', nor can anyone else.
According to the Ayn Rand Institute:
The government acts only as a policeman that protects man's rights; it uses physical force only in retaliation and only against those who initiate its use, such as criminals or foreign invaders. In a system of full capitalism, there should be (but, historically, has not yet been) a complete separation of state and economics, in the same way and for the same reasons as the separation of state and church.
This may sound good on paper, but it ignores the fundamental roles of government as defined by the Constitution of the United States:
We the people of the United States, in order to form a more perfect union, establish justice, insure domestic tranquility, provide for the common defense, promote the general welfare, and secure the blessings of liberty to ourselves and our posterity, do ordain and establish this Constitution for the United States of America.
So, from Rand's perspective, a good governance system for the United States would abolish the Constitution and institute a new set of roles, eliminating the desire to form a community of mankind, ignoring the need for domestic tranquility, ignoring the general welfare, etc. Capitalism in these terms is of course an economic system, but not a social system, and certainly not a system of governance worthy of discussion.