In my country, there was not so long ago a case of a person wrongly accused of murder[0]. He spent 18 years in prison, despite there being no convincing evidence of him committing the crime. The people invested in the case wanted to have a scapegoat ASAP. Cases related to pedophilia are often very emotionally-charged, given the nature of the crimes. It can easily lead to hastily made decisions that can ruin many lives.
> Not to mention how infinitely unlikely it is that _several_ of your photos would be similar enough to known abusive material to be flagged.
Given enough time and enough attempts, there still is a possibility of something like that occurring. And this is with an assumption that the algorithm used will be correctly implemented with no false positives at all – something that I doubt even a manual analysis by humans would be able to achieve given the volume of data to check.
[0]: https://pl.wikipedia.org/wiki/Sprawa_Tomasza_Komendy (in Polish)