Many of us must be aware of this and left it as it is considering that this is how OOB CRM functionality works for quick find.
The QuickFind search functionality (in its current form) does not return records from within the selected view. Instead, it spans its search across all active records within the selected entity.
I found this interesting tool “Quick Find on SelectedView” on CodePlex that addresses this issue.
There are few limitation mentioned clearly on the site which should be considered before using it.