TOOL-BARS: How do toolbars manage to insert new settings on to the users computer when legitimate programs can't/won't do it?

I accidentally installed Ask Toolbar, and it changed my Homepage,Search engine and added some extra stuff. It did all this without alerting Google Chrome!

But when I try to install a legitimate search engine like DuckDuckGo, I have to do a lot of manual work compared to the Ask Toolbar which seems to automate installing the settings.

I was wondering why does't DuckDuckGo use the same methods as Ask?

Is it due to security issues of sorts?