Why is it so much easier to enter incorrect new data than to fix incorrect existing data?

I devote a lot of my spare time to completing or fixing credits of some foreign genre movies. Unfortunately, for me, the experience has often been very frustrating. It is very easy to add new data to IMDb. These additions do not need proof and are almost always approved within hours. As a result, incorrect information often ends up in the database, which was entered by less conscientious contributors. What bothers me is that IMDb makes it very hard to fix obviously incorrect information such as misattributions. Although I'm providing screenshots of the credits (and in some cases even PDFs of the complete credit roll which is a lot of effort for me) in my contributions, they're are often denied with "Your contribution has been declined. We have been unable to verify your contribution." and no further explanation. Apparently my laboriously formulated explanations are not being read or understood properly. Maybe my English is just too bad, who knows. After two unsuccessful attempts, I usually give up in frustration and leave the wrong information in the database. I understand that the database should be protected from tampering, but why make it so much easier to enter incorrect information than to correct it? I'm slowly getting to the point where I'm saying it's just not worth all the effort. If IMDb doesn't want to benefit (for free) from my knowledge and my time, then so be it.