For reference, I don't store pirated content, rather content that I have a license for, but cloud providers have no way of knowing that. Unfortunately the dispute processes are unreliable, so when it's time to backup a media project, I play it safe and encrypt.
I'm pretty sure that they just assert that the backup is illegal even if it came from a licensed copy. One argument (used by Nintendo IIRC) is that the official media/servers are too reliable to require backups, and thus anything purporting to be a backup is really for another purpose and thereby not exempt under the statutes authorizing backups.
My entire Nintendo DS and 3DS cart collection was stolen in a break-in at my place. You can bet that instead of repurchasing I simply bought a flash cart.
I wouldn't trust such services to respect your rights in any capacity. In fact, I would argue that the "our incredible journey" trend is a form of property damage (a storage rental place can't just burn their store to the ground with customer's posessions still inside).
> Respect copyright laws. Do not share copyrighted content without authorization or provide links to sites where your readers can obtain unauthorized downloads of copyrighted content. It is our policy to respond to clear notices of alleged copyright infringement. Repeated infringement of intellectual property rights, including copyright, will result in account termination. If you see a violation of Google's copyright policies, report copyright infringement.
Given that they cater to businesses, I don't think they could do automated scans.