Recently, I have voted to reopen this question: Since yesterday, I can not access mercadolibre.com.ar anymore but it does not show in my activity list. I have requested this on the question page instead of from review page. It seems to me that it maybe a bug? Is it a bug? Other than that, what type of activity do not show on the user activity list?
If you look at your activity list in your parent profile, it's broken down pretty well. Votes, for the most part, don't make a lot of noise there.
Sure, if you down-vote something, folks will see a small reputation change in your reputation history. But they don't see this if you up vote, vote to close, vote to delete, or vote to re-open a post. That's a little too much of a ticker tape about how you use the site, and I think quite a few would be a bit uncomfortable if other users had the ability to track your every move.
Everything you do on the site will affect the 'last seen' portion of your profile, letting folks know if you're still around (useful if someone leaves a comment for you and wonders if they should stick around another 20 minutes or head outside). While who voted to close / delete / re-open something isn't private information, you need to be on the particular post where the vote was cast in order to see it.