Windows 7 no longer tries to guess application size and other information
Back in the old days, if an application did not provide information like its Estimated Size or Install Date, then the Add/Remove Programs control panel tried to guess the values by searching your hard drives for files and directories that bore a superficial resemblance to the application. (Note that I use the word drives in the plural. It actually searched all of your drives, because some applications may have been installed to secondary drives. I can imagine the bug report that led to this extended search. “I installed LitWare 2000 to my D: drive, and the Add/Remove Programs control panel shows no information for it. You should have found it on my D: drive, because (like many power users) I install all my applications to my D drive to maintain free space on my C drive.”)
Time passed, and the name of the Add/Remove Programs control panel changed several times. It became Add or Remove Programs in Windows XP, changing the slash to the word or. In Windows Vista, its name changed to Programs and Features, but at least the name has been stable since then.
In Windows 7, the “search your hard drive looking for the application” fallback algorithm was removed. If an application did not provide information such as its estimated size or install location, then Windows now just says, “Well, tough on you.” My guess is that the search was removed because the vast majority of applications now provide the information directly, so the extra cost of trying to hunt it down for the last few application was not worth the benefit.
There is still one tiny thing that Windows will guess: The installation date. But it doesn’t have go hunting through your hard drive to guess that. It merely infers it from the last-modified date on the uninstall metadata itself!