It is important as to whether the issue is a controlled document or if it is data collection. Changing controlled documents with white out - that becomes interesting. Did you change all of the copies? Did it need rev-ed? Some systems allow "temporary" changes as long as they are initialed and dated. Usually that will pass muster (do what you say....). But, if you see a print on the floor with white out and no initials - you have no idea if a person with the appropriate authority made that change. That would not pass.
As far as fixing data collection mistakes, you may pass an audit if you allow white-out in your procedures. Firestone may have not liked to put data on the overhead in court looking like that....but, that is beyond the discussion here.
Nothing is ever illegal until you get caught. Pencil is never a problem until one sheet gets smeared and a customer or third party auditor gives a finding for illegible document, and you need a corrective action. Until then, you are free to use crayons if you wish.
First - we are a job shop - and we work to our customer drawings. We are very diligent about protecting our customers information. We do not use customer names, we assign a number to all our customers. ALL drawings received from customers have the customer name covered with white out.
Second - When we perform a first articles on all new parts. When out of tolerance conditions are noted - the engineer corrects the part program, re-runs the part and we re-inspect the out of tolerance conditions and report the corrected findings on our original first article report. Some of our customers request a copy of our first article report - so in those cases, we "clean-up" the report - because to an outsider - the report would look very confusing.
That is just a "bumper sticker" statement. The statement was not a matter of my ethical view, but rather a more "worldly" view that there are people who are willing to do a lot of "illegal" things, and will accept the interim consequences of what people may think of them. They do not really feel any remorse until they are caught and face the more dire consequences. Sometimes, even then they do not feel remorse for their actions - just for the fact they got caught. You see it in the news - and audits, in a less legal manner - all the time!