What I mean is that I see a ton of RM images that have copyright protected content - iphones, logos, even a DVD cover, etc. How is this stuff sold as stock photography?
Because it isn't illegal to do so. RM and RF are just terms to describe how an image is licensed, it's nothing to do with the content of the image.
Is it somehow being sold as editorial only?
Maybe but that's only because the site it's being sold on requires it to be so because of their policy. Not the case on Alamy unless you set an editorial restriction yourself.
It seems that images like this could not be used without a release except for in very specific journalistic instances.
Yes and No, as others have pointed out it all depends on the end usage.
I don't want to confuse you (it will and many others to) but there is no law to say that a copyright or trademarked product can not be used in a commercial sense, it happens every single day in thousands of adverts around the world - confused? To understand how you need to understand copyright and trademark law, which is very hard if your knowledge base is from the stock industry. No stock agency in the world would be able to control or indeed specify the exact terms to what, where and when certain products in an image could and couldn't be used, therefore they make general terms to protect themselves plus to a certain extent the contributor and in the case of Alamy they ask a general question as to whether anything in the image requires a property release to use the image commercially, it would be more accurate if they asked 'Is there anything in the image that
might infringe on another parties IP rights' and as Racephoto pointed out above they then issue a more accurate disclaimer to buyers.
And before you or anybody else asks for examples, next time you watch TV carefully examine the adverts especially the ones shot in a city or home, look out for background objects and see how many you can spot that would likely be trademarked, copyright or design protected, the people who made the ad won't have got a property release for those objects because they don't need one.