I think the point is that manufacturers will assume that folks have already got a suitable charging lead. So when you buy a new gizmo, or at least if it's by a relatively environmentally friendly manufacturer, it won't come with yet another lead. Because all leads are the same! Imagine if you bought a new washing machine and it came with a different design of plug on it that wouldn't fit in your wall sockets?
At the moment, if you buy, say, a Fairphone or a Suri toothbrush (I've got one of those, it's excellent - 30 day battery that's replaceable, every part of it including heads recycleable - they even provide a post bag to send heads back to them) it doesn't come with a lead - you have to pay extra but they try to discourage you from buying another as it'll probably end up in landfill.