For installation, maybe. sometimes.

(The biggest issue I'm aware of is that if you have an old version of the app indexed anywhere on your root drive - for example in ~/qa/app-v1.02-DO-NOT-DELETE - it will literally stomp over that instead of installing the app to /Applications, even if the developer manually specified the install location as /Applications in the manifest.)

But for uninstallation, not a chance. There's no Mac equivalent to Add or Remove Programs on Windows - once you install a PKG good luck uninstalling it.