It is not just an example of being asked to do one more thing that you don't want to do, and it is incredible that so many libertarians have resorted to seeing our circumstances in this way.

Paying for roads with taxes is not the same thing as changing all the standards having to do with modern bodily autonomy. A standard which causes the service of one's and everyone else's body to become an asset for the state in ways not seen before. So what does that mean? Public measures can be declared which continuously require you to fulfill some part of it. Some would say that some form of participation is always being asked of you, thus this is no different, but what sort of things are asked of us?
- Paying taxes, filling out census, paying to survive in community, economic participation
What else? None of these require access to your body, internally, require you to modify your physiology an cause you to take a direct material risk. Particularly while not being given the option to express genuinely informed consent.

And what this does is not just a matter of incurring some risk from an adverse reaction / reaction to having administered a treatment, but to be acknowledging a new standard as to what can be repeated and accepted in society. It is now to be more commonly accepted not just that access to one's body be made available, but that one's opinion on the transaction is completely irrelevant at best, and hostile when not compliant in the worst.

This sets the precedent that one's thoughts and ideas are not only to be disregarded in the face of public and civic disagreement, but that they are even irrelevant in the matter of making decisions for one's own self interest.

And all for a standard which itself need not scratch any past precedent, but can be reformulated without one's opinion as well. At this stage, you are only useful insofar that you have the capacity to not be burdensome to the state.