I finally found information about superglobals not being found in $GLOBALS:
https://bugs.php.net/bug.php?id=65223&edit=2
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[2013-07-09 12:00 UTC] johannes @php.net
[...]super-globals (aka. auto globals) are not added to symbol tables by default for performance reasons unless the parser sees need. i.e.
<?php
$_SERVER;
print_r($GLOBALS);
?>
will list it. You can also control this using auto_gloals_jit in php.ini: http://www.php.net/manual/en/ini.core.php#ini.auto-globals-jit
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http://www.php.net/manual/en/language.variables.variable.php
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Warning
Please note that variable variables cannot be used with PHP's Superglobal arrays within functions or class methods. The variable $this is also a special variable that cannot be referenced dynamically.
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