[teilo]

Yes, this does need to be at presentation time. In monospace, this may make sense, but that's not how text layout works. A space is dynamically sized.

Granted, there are overloading issues, but we have had decades to refine text layout engines to account for this. Major text layout systems, including those used in publishing, need to be able to dynamically adjust spacing based upon context. Software such as InDesign does this, and it is a standard part of workflow to replace all double-spaces with single-spaces.