Technically, the breakaway cable should be attached to the frame of the towing vehicle, not the receiver hitch. there have been instances where the receiver hitch attachment failed, allowing the receiver to depart from the towing vehicle. With the cable attached as pictured, the emergency brake would never actuate in such a scenario.
Realistically, I don't know anybody who does not attach the cable to the receiver.
Including myself.
I think the pictured attachment is entirely adequate.
The length of the cable is another discussion topic, which I won't touch at this time...