I’ve seen this quite a few times, and it drives me nuts every time.
It’s very common for theme or plugin developers to setup options for their system in a large array and then make that array globally available. Ignoring whether developers should populate global variables or not, this is a perfectly fine method of gaining access to your data (but not always a good idea). However, your global variables should always be named in such a way as to NOT cause conflicts.
This evening I found this in a very popular commercial theme:
$data? Really? This is a really, really bad idea because it is such a common variable name, which means that any other plugin or theme that decides to also follow this poor naming convention will cause a possibly dramatic conflict of global variables.