Android allows that in settings. But AFAIK it's just a software setting, the data lines are still physically connected. The reason why there's no physical hard

Android allows that in settings. But AFAIK it's just a software setting, the data lines are still physically connected. The reason why there's no physical hard disconnect available in settings comes back to what I said earlier, cost and convenience from the manufactures' perspective. They don't want to spend 2 cents on some mosfets for HW disconnects, and they don't want to nag the user every time they plug in the phone to charge as that would hurt the UX. They want the device to sync up automagically to whatever device you're pugging it into. That's what USB was designed for, convenience. Plus, if you nag the user every single time they plug in the USB with a security prompt, they will just get desensitized and instinctively click 'YES' all the time.