It is trivial to commit someone else’s patch as your own and without any history if you want to write the script. Just not that hard.
That is the bigger problem than the way that bills are presented to the public.
For most people, I assume they're talking about the federal government when they say things like you said. I just want you to know that it's already open and available. For straight legislation - congress.gov tracks bills and gives you the text of most things. Whereas federalregister.gov gives you regulation changes.
Yes, there is a day or two delay on congress.gov from introduction and when it is transmitted from the GPO to the Library of Congress. But overall it's pretty quick.
How come no one ever slips a good thing into legislation when they can?