Sable -Yes, that's exactly right; and, it all comes down to when someone starts to make money publicly on another persons intellectual property, and how much money they are making - or, perceived to be making.
Most people mistakenly believe a Copyright affords the holder much more power than it actually does. A Copyright really only provides for two things: 1) The Exclusive Right-to-Copy; and 2) The Right-to-Defend those Copyrighted materials. This Right-to-Defend merely means the Copyright holder can now pay lawyers money to defend their Copyright materials through the courts; and this can get quite costly if it has to go all the way.
Even having a non-house lawyer send out a boiler plate Cease-and-Desist can cost a couple of hundred dollars - IF it has any real teeth behind it - and most do not have any real teeth to them - because most companies simply mail out "paper tiger" C&D's, hoping the recipient will be intimidated into willfully complying; as the Defender does not have the money needed to take it to the next step.
If that does not happen, now it gets like a Poker game; as the C&D-issuing Defender has just bid X, and now the infringer is either going to Fold (comply), Raise (return an answer from their own lawyer stating the Defender has no legal right to defend), or Call the Bluff (ignore the notice, and dare the Defender to pony up the money to take it to the next level.)
So, for a small company, the big problem for the Copyright Defender manifests when the person who received the C&D ignores it and continues reproducing and engaging in commerce with those materials; as now the Defender has to go to the next legal step, which is to file for an injunction and/or file a suit, claiming and being able to document and show damages to their IP (not always easy)... and this proposition is not cheap, at all.
In the case of Trademarks, if the Holder does not take action to defend, they run the risk of losing their mark. In the case of Copyrighted materials, the holder who does not take action to defend, they run the risk of having their materials fall into the Public Domain.
In short, you life is usually better - and your wallet more full - without lawyers involved; so just do the right thing by others and their property; especially if money is involved. - Sherm Natman