A good question about data (mis)alignment is "Where did it come from?". So here's a reasonably detailed answer to that...
If the compiler has generated the code for you and you've not done anything "weird" then the data should be correctly aligned. So most apps don't have misaligned data, and most of the time you (as a developer) don't have to worry about it. For example, if you allocate a local variable, or a global variable, then the compiler will correctly align it. If you cast a call to malloc() into a pointer to a structure, then that structure will be correctly aligned. And so on.... so if the compiler is doing all this correctly, when could it every be possible to have misaligned data. There's a bunch of situations.
But first let's quickly review the -xmemalign flag. What it actually tells the compiler to do is to assume a particular alignment (and trap behaviour) for variables where it is unsure what the alignment is. If a variable is aligned, then the compiler will generate code exploiting that fact. So the -xmemalign only really applies to dynamically allocated data accessed through pointers. So what does this apply - the following is not an exhaustive list:
The take away from this should be that alignment is not something that most developers need worry about. Most code gets the correct alignment out of the box - that's why the example program is so contrived: misalignment is the result of a developer choice, decision, or requirement. It does sometimes come up in porting, and that's why it's important to be able to diagnose when and where it happens, but most folks can get by assuming that they'll never see it! :)