When I connect my android device to a PC, it has several options for the "mode" of connection. Does anyone know the reason for this? Why would anyone want file transfer to be unavailable on a USB connection? Is there anything gained by disabling file transfer? If not, then why is it not always enabled? I know there is a workaround with developer mode, but I would like to understand why this problem even exists.
My guess for this behavior are security and privacy concerns.
If you connect the phone to an USB port mounted somewhere where you can't control if it is connected to a charger or a PC it makes a difference if it is a PC that automatically gets full access to all you photos, videos,...
Micro PCs can be placed even in cases of charger size so considering that any USB device you connect your phone to could directly steal a large number of your private data - would you really want this?