Geotagging is something that tends to be on by default, and lots of people aren't aware they can shut it off. (or that it's happening in the first place)
The Twitter app properly communicates when you're geotagging your tweets or not, and allows deactivation using a simple click before you submit. If that's all it takes for privacy, then I'm ok with this. Facebook is much more sneaky. I would be curious to know how many protesters shared their location without wanting to. Witnessing my family of tech-unaware people, privacy leaks is a monster they're all afraid of, thanks to headlines of media, and they often ask "Not to be tagged on fb" or "How can I be sure that ...". Protesters are probably even more conscious of this.
Defaults are strong and powerful, though. This is the main issue which companies like this have taken advantage of.
Many users don't know that something is on by default, and if the default is to geotag, people will nearly always forget to disable the geotagging.
You or I might know what it means when the 'place' icon is highlighted during a tweet. Non technical users might not understand the implication of thier actions.