I've used numerous Huawei USB modems with the Pi 1,2 and 3. I have a dedicated script that checks the lsusb output and on finding a modem that matches the usbmodeswitch data file does the switch and connect with sakis3g. This creates a ppp interface to the internet.
I recently bought a ZTE MF710M USB modem and was surprised that with zero commands it set itself up as a "usb0" interface with IP and is fully connected.
What is this magic? Is this something new? Why do all USB modems not work like this?