In my view it is a fallacy to equate offences against physical property with actions relating to intellectual property. Let's take the example of larceny and try to apply it to copying an epub file. A nice simple explanation of the elements of larceny can be found here:
Findlaw Elements of Larceny
To prove larceny the prosecutor must prove beyond a reasonable doubt:
1. The unlawful taking and carrying away;
2. Of someone else's property;
3. Without the consent of the owner; and
4. With the intent to permanently deprive the owner of the property.
It is very clear that neither 1 nor 4 can be proven since they have not in fact occurred. I suppose if a pirate steals someones computer or hard drive and carries it away with the requisite intention it is possible to argue that larceny has occurred not only in relation to the hard drive but also the intellectual property stored on the hard drive.
But nothing belonging to the owner is taken and carried away by simply copying a file. And the owner is not deprived of the file since it remains undamaged wherever it is stored. The point I am making is that viewing intellectual property by way of analogy to physical property only goes so far. It is understandable why rights holders equate copyright infringement with theft, since they want to attach the same odium to copyright infringement, presumably in an attempt at simplification as even young children are quickly educated to understand that theft is wrong.
Likewise, as st_albert pointed out in his reply to theducks in this thread, breaking and entering is not a good analogy for accessing a calibre server exposed to the web, whether or not there is any security on that server.
Copying ebook files without the owners permission is not larceny. It is copyright infringement, a fundamentally different thing. Accessing another computer over the internet without authorisation is not breaking and entering, though it may be one of a number of different offences created in different jurisdictions.
Whether copyright infringement is morally equivalent to larceny, or accessing a computer without permission to breaking and entering, is a different argument and will no doubt attract a variety of views. But reasoning by use of analogies between these concepts is of limited use and usually attended to attach the odium of one crime to something fundamentally different.