As I said in the comment you're replying to, there are lots of times I write down that can be usefully processed without being reduced to absolute time. My text editor doesn't know how to do that. (Much.) I'm writing here precisely because I think it's a problem that often needs to be addressed precisely and accurately, and neither automatically falsifying data on input, nor making an application that's harder to use than pencil and paper, is an acceptable solution to the problem.
You're doing a bad job of distinguishing between a feature you personally want in an application, and the actual problems associated with storing times. As has been pointed out, there's no such thing as a time without a timezone. '12:30', the thing you want to write, is just a string. Acting like it's more than a string in your application is fine - strings are very flexible - but that's a completely different topic than the one at hand. You don't seem to be grasping this.
I guess the challange is to enter a precise time using a computer, and make it as easy as writing an imprecise time on paper.
I don't know where to go from there. On paper, you can assume than a time without a timezone is in localtime. That is fine, since it takes effort to move paper from one timezone to another. If you know the paper is from a different timezone, you might switch your interpretation, even without the timezone stated explicilty.
