When you use public roads, why shouldn't I be able to track everywhere you go and tell the world exactly where you are?

You can... who's stopping you?

Yeah, it costs money but you can buy someone's location data in real time.

Because it's not an airspace where speed/visibility are important for a variety of reasons... FBOW moreso post 9-11

Evidently not. I live on the Chesapeake Bay. I see many Coast Guard and Navy vessels regularly that are not broadcasting AIS signals used for the safety of vessels nearby. Yet others do. I also see many military aircraft not broadcasting ADS-B, yet many are.

The vast majority of military ships and aircraft operating domestically have collision avoidance (ADSB/AIS out) turned on. When conducting sensitive operations they can turn it off, but must be in direct communications with the appropriate controlling authority and almost always have a primary radar system active.