From the perspective of consumers and society, objections to how these businesses operate is understandable. But it's also true that these companies are businesses, and that being internet businesses doesn't mean they are any less subject to profit motive than conventional businesses were.
When I was young, I bought a lot of public-domain books because they were cheap and I didn't have much money. Buying an out-of-copyright classic for $5 was a lot easier than buying a $15 copyrighted modern classic. Today I would just download them for free on the Kindle, or gripe about paying a dollar or so for those that weren't completely free. I don't remember many people complaining about houses like Dover Books profiteering from public-domain works. Nor do we really complain about video companies selling (crappy) DVDs of public-domain movies like Penny Serenade.
But when it comes to digital versions distributed on the internet, we tend to believe that things should be free. We get statements saying that "our online services have looked less like the public platforms we want": but the problem is that these are not public spaces (perhaps we would like them to be, but they're not), they are not publicly subsidized, and the organizations that run them are subject to laws. Maybe we don't like take-down laws, but the alternative is potentially massive liability for these hosting organizations, exposure to which would result in only curated and vetted media being made available: forget about your soundcloud upload. And maybe this is a viable alternative: when a company digitizes and uploads media themselves, they have complete control of what gets put up and can verify the copyright status. But it seems like a much more expensive way to build a media repository, and to the extent they have done the hard work of digitizing everything I'm not sure they shouldn't be allowed to control how it is used (otherwise you will have more of what general Books did: scraping the repositories of other scanners/digitizers and monetizing the content at the expense of the original digitizer).
Of course, some mechanism for enforcing the takedown-fraud rules would definitely be a good thing, but I don't think this adequately addresses the greater issue of how we conceptualize the nexus of public domain and private enterprise in the internet age.