I have access to the source of tons of stuff, and yet I can't fix it.
Not without spending months on understanding their codebase and going out of my actual projects and work.
(And even then, my fix might not be accepted upstream, so it could be invalidated with any major or even minor version update).
That other's have access too, so someone might fix it, also doesn't work that much. Tons of projects, even extremely popular ones like GTK have but a few commiters, and tons of open bugs.
Two recent problems I had with LaTeX:
* If you put a \dfrac inside a table, the table thinks that the fraction is smaller and the line of the borders of the table collide with the numbers.
* If you need a different header height in your first page, you need some black magic macrology to get a not so good solution.
Here's a very simple way to do it for DateListPlot:
So the OC could actually rewrite DateListPlot to add error bar support, if he wanted to. He could even overwrite the original MX file in his installation once he had done this, if he so desired.
Even thought it's true, probably he couldn't legally distribute his own modified copy of DateListPlot. Right know you can hack together error bars for a plot even if you only know the output format of DateListPlot (FullForm and patter matching helps a lot).
Thanks for "Spelunk", it's awesome.