for me it's
This is one of the largest, most obvious flaws with android. Manufacturers originally used /mnd/sdcard as the default location of the ACTUAL sdcard. Some time later in Android development though, applications started having a lot of problems with apps that were on the SDCard. So, manufacturers started partining the internal memory. They had part of it 'system', and part of it partioned into 'sdcard'. this made most apps work MUCH better. But - it's not really the SDcard. So, when you put in an actual sdcard ... it has to be something different. This is one of the areas where not haveing actual standards has hurt android development.