Stuff like this:
Note that A can have a tapped termination too. That helps when CM filtering is needed, otherwise there's no impedance to filter against.
B is useless unless the shield is tied both ends. An open shield just lets in all the CM interference induced along the length of the cable. You might as well not use it, and indeed, you almost never do (Ethernet is fine even in industrial settings without shielding).
There is a negligible improvement in DM noise, because it's already twisted to cancel out interference. (Note that situations which break this assumption, like closely spaced cables of equal twist rate, or short spans with proximity to noise sources, will benefit more from the shield.)
The ground loop can be avoided at low frequencies by using lots of bypass caps to achieve a similarly low-inductance AC grounding, and it can be avoided at high frequencies by using ferrite beads on the cable (effectively making it a 1:1 transmission line transformer, matching signal and shield currents).
C is doubly isolated, though it may not need to be; the receiver should use a tapped termination, which will extend CMR significantly.
Single isolation is shown in E. With grounds shared by shield, a tapped terminator isn't needed, but you can if you want.
D is the same thing but with the shield joining the iso grounds. May not be permissible, are shields required to be galvanically grounded? Idunno. Anyway, with both sides isolated, a ground can be added to the shield anywhere along its length, no problem.
F shows the better version of what they were kinda maybe going for. The one side shares its ground with shield, no signal quality issues there. The far side sets the ground reference (like a modification of D), while maintaining the isolated receiver to improve CMRR even further, and using a tapped terminator in support of that.
I suspect this was actually pulled from a LVDS datasheet, what with all the transmitters and receivers being fixed, and the grounding being weird? Possibly RS-422 but these measures should rarely be needed with the wide input range. RS-485 is a bidirectional bus so might be shown with transmitter and receiver only for simplicity, or to explain one phase of communications, but in reality both devices are transceivers.
Isolation and shielding are more important for low voltage buses (LVDS, HDMI, USB, etc.), where the CMR is only the supply rail, if even that (all of a volt or two). Industrial buses like RS-422/485, CAN, etc. have extended CMR built in via input divider resistors, so only need shielding or isolation when the ground loop or interference is expected to exceed that range. (AC coupled buses like Ethernet, need none at all, as the transformers provide the CMRR required.)
A reminder that, in the above, CMR(R) is frequency dependent. If you isolation barrier has substantial capacitance (a DC-DC isolator might be from 100s to 1000s pF, less for good low-C or high-dV/dt types, more when you add as much "Y" type capacitance as you like), then for the base case (like, the original 'C' one?), CMR is good at DC, dropping off sharply at the RC cutoff frequency determined by receiver input resistance and isolation capacitance.
This is why the tapped terminator makes such a dramatic improvement. Instead of 10 or 100kohms between pair and local GND, it can be merely 25 ohms (common mode).
Tim