If all of the files are owned by me, the user... why does splunk's installer need to elevate privileges?
http://support.apple.com/kb/HT2558?viewlocale=en_US
Installing software in Mac OS X requires an administrator account name and password.
When installing software that uses the Installer included with Mac OS X, Installer displays
a dialog with an authorization message (even if you're the only person using the computer):
"You need an Administrator password to install the software. Click the lock to make changes."
http://support.apple.com/kb/HT2558?viewlocale=en_US
Installing software in Mac OS X requires an administrator account name and password.
When installing software that uses the Installer included with Mac OS X, Installer displays
a dialog with an authorization message (even if you're the only person using the computer):
"You need an Administrator password to install the software. Click the lock to make changes."
perhaps, or perhaps
But Alex is correct. All users must authenticate to install apps, even with the "drag/drop" method. If you don't get prompted, its because you are admin--and really should be running as a "normal" user as its a better security protocol
Often, Mac users run as "admin". They are used to just drag/dropping from a DMG in to their Applications folder without a prompt for applications that don't have "installers"--like Skype.
Apps that do have installers usually do make you do secondary authentication when the run--hence the password prompt when you install Splunk.
However, Splunk's installer doesn't appear to do anything other than move its files in the "/Applications/splunk" folder so it would seem Splunk really doesn't need an an installer per se, and should probably follow the conventions of a typical OS X app.