Automatic 'Retry Download' and resume

[Excess-Code]

Downloads of large files often fail mid-way through and offer the 'Retry Download' function to resume the download. Can we pleas have an automatic "Retry Download" function built in? Considering the ubiquity of this problem and the fact that it's worse for longer larger downloads makes this basic retry/resume function a real necessity.

This seems obvious and yet no download manager seems to implement it.