Locks only keep honest people honest.
DRM looks more a profit-making strategy for large corporations like Amazon who can use it to restrict competition. It’s well known by this point that DRM does not prevent digital piracy, the argument usually made for it. What it does is prevent book buyers from moving their files across reading platforms.
However, I am really satisfied with Amazon because my ebooks are "Simultaneous Device Usage: Unlimited" at least inside the Amazon ecosystem.
Probably they have some other restrictions, but for instance I have never tried to print files or to modify the cover image; I don't care these things, I am more interested in sharing underlined text, notes, and comments on my devices, I can do it so I am really happy with my ebooks.
I am not against the digital rights management as at least DRM acts as a deterrent to piracy, the problem I have is against country/region restriction because I cannot buy an ebook without telling Amazon a lie.
Why should I have to tell Amazon that I live in the US to buy a book which otherwise I couldn't buy in my region? It's also annoying because you have to edit your account and this may affect your physical orders.
You can find an .epub online, which is the common ebook -without region restriction- format, but the Kindle can't read it "natively". That's okay; you can convert .epub files to Mobi files for the Kindle to read, but there is a third solution!
You may purchase MOBI files directly from publishers and "sideload them onto your Kindle" via Amazon registered email. For instance,
Smashwords does not encrypt its ebooks neither apply any region restriction
