WEEE Directive

I have one additional point on mobile phones, which people renew regularly, and particularly on the interfaces on them. When disposing of a mobile phone, there is also the plug that goes into the wall. What goes into a mobile phone is different even within the same company—Nokia seems to have several interfaces on different models. Why cannot there be common interfaces so that people can reuse the plugs and the stuff that goes into the phone on different models, or certainly on models by the same company?