Note that the Place Pages have had a free link section for quite some time now: Nearby places you might like
The nearby places aren't ads but are algorithmically determined free links, and it could be argued that they're more threatening than the ads, because, from what I've seen so far, they're for nearby competitors and they're a lot more relevant than the ads are. I think the ads have been around for a while.
These pages are prone to hijacking and external edits unless the owner "claims" them. I recently reported the hijacking of a page of a place I patronize (someone changed the url of the website), and it was fixed quickly.
Review content is subject to abuse everywhere. You can flag the Google reviews as inappropriate, which is a better break than many review sites give you.
The short answer is that Google can do what it wants. If you didn't invest the time to spruce up your Place Page, there would probably be a default page for your business and you'd still have to contend with the other competitor information.
We (large banking group) recently had a bad experience. There are several hundred ATMs and many dozen were showing a rival bank's name in the snippet (when viewed in Google Maps) and the detailed page had the locations of a rival bank many times over. Even the URL in the "Details" area was that of the other bank. We deleted all entries and reuploaded. Things were good for a while. A month later, the rival bank's content is back.