The difference is that companies are voluntary associations of individuals. A government is a monopoly of force and justice; it can exert its authority even on those that have not explicitly (via a free contract) agreed to it.
Today that may be so; but prior to 1914 it was possible to move around anywhere in Europe (including the UK -- excluding the Russian Empire) without a passport or identity documents, and pretty much legal to settle anywhere. While the cost and difficulty of moving back then was greater than it is today, states had very porous borders and it was practical to vote with your feet (as in fact my grandparents did).
The first world war put an end to the old order and made nationality non-discretionary -- and we're still dealing with the fallout today (as witness the permanent floating founder visas thread on HN).
I remember that from the start of Niall Ferguson's The War of the World - in 1913 the world looked quite a bit like it does today (at least from a "globalization" perspective).
Everyone has obligations that tend to reduce their freedom. The ones who think they don't are called psychopaths.
In personal development, an early stage is to understand that you can be independent. E.g. you can choose how to act and how to react to the outside world.
A higher level of development is to realize that we're inter-dependent. No man is an island.
There will always be constraints on our options. I don't like it, but I'm getting used to it.
There is no absolute freedom, and there are no truly free contracts.
