Except in some countries (I believe the US included) you are not supposed to delete them, since the law says you should quarantine them (i.e. remove them from the platform, but keep them as evidence somewhere else as evidence) and call the police. Then they would be in the middle of a CSAM investigation, which would be really disruptive if there isn’t a relatively big team behind the service. And then it would require handing a bunch of user data to the police, which is a deal breaker for lots of users. I don’t blame admins that are running the instances on a volunteer basis for not wanting to deal with all that.
Arabic Numerals usually refers to Western Arabic Numerals (in opposition to the Eastern Arabic Numerals in the image you shared).
This reminded me immediately of The Coffee Machine short story published last year. Reality manages to be stranger and weirder than fiction.