Sure, that's easy: everything is copyrighted. The difficult part is determining whether the uploader can legally share the copyrighted material, which is just as likely to prove impossible to automate with accuracy and precision as the detection of personal information.
How would that have that effect?
Someone correct me if I'm wrong.
More realistically, this is a problem that has no easy technical solution that originates from a law that still isn't adopted.
If I were an owner of such platform, I wouldn't worry too much about it now. In a year... maybe.
Here in the UK, these sorts of laws have had, as far as I know, zero enforcement.
http://nocookielaw.com/ https://silktide.com/the-stupid-cookie-law-is-dead-at-last/ https://silktide.com/dear-ico-this-is-why-web-developers-hat...