|laziness, impatience, and hubris|
No reason to make it harder on people that way - reason is simple: people who violate encapsulation should be beaten with sticks anyway.
Nah, I'm just kidding. But anyone who is bypassing your api to access values themselves (perhaps just because you accessor methods do extra stuff?) should know that they "void warranty if opened" as it usually says on most electronic boxes you can buy. They are on their own. And if that turns out to be a bad thing, well, you did tell them, yes? By having accessor/mutator methods, you specifically declare that this is the way the data should be accessed.
Even heavily guarded languages like java provide the same capability to directly access just about anything inside a class - if you choose to. In java, it is called reflection, and as mentioned above, it is possible in just about any language, really. If you want to.
I don't recall exactlty how, but I think that the Camel book had some nifty examples on how you actually could create truly private data, with no possibility (apart from patching) to access the properties or data at all. Take a look at the Object chapter (I think) of that book if it is important with private data.
Life tends to be so much simpler if one just follows the guidelines that are set up. But if you need to break the rules for one reason or the other, it should be easy to find the data you want to manipulate - which might be a reason not to name the property too differently. So that people that wishes to do so, can more easily follow tthe code and extract what they want... with warranty void, of course. :)
You have moved into a dark place.
It is pitch black. You are likely to be eaten by a grue.