Right of way
Interesting topic and perhaps easily misunderstood.
'Right of way' codes do not describe rights in the classic sense. For example states grant the privilege to operate a vehicle on state owned roads, so rights are not involved in motor vehicle right of way. Somebody touched on duty which is closer to how the codes are written.
91.113 is where we go for aircraft. I haven't a clue where or even whether civil or federal code might be found for intramural meeting situations.
Then there are operating procedures written by organizations like airports and golf courses and the like.
Consider a blind person in a meeting situation with a sighted person operating a vehicle and expectations easily get turned on their head.
Even our own rules under 91.113 are often misquoted. For example 91.113g speaks to the special circumstance of an aircraft on final. That aircraft has the right of way over all other aircraft inflight or on the ground, and all others finding themselves in that meeting situation must maneuver clear. So an airplane on final would have the right of way over a balloon in a meeting situation. Yet many would argue that an aircraft at an uncontrolled field who has been in the pattern and is on base has the right of way over an aircraft on final from a straight in. Such a person might try to quote an AC or AIM, but 'right of way' only exists where it is codified as right of way. In fact I had a email exchange with an active co-author of AC 91-66B at the FAA who claimed that the AC gives right of way to the aircraft on base! Even the authoring desk didn't understand that in its seminal definitions of Advisory Circular structure AC 00.2-13 declares that: "the contents of an advisory circular are not binding on the public" By contrast we know that FARs are binding. If anyone noticed, that part of 91-66 that lent confusion has since been re-written.
When properly understood, 'right of way' codes exist to mutually deconflict meeting situations by standing procedure. Yes, they have an after the fact component but that is not where the value lay. The 'stand on' and 'give way' participant in a meeting situation each have a duty under law that provides deconfliction and is pre-coordinated. In the case of a mower vs an airplane if the airplane continues toward the recognized meeting situation there probably isn't anything the mower can do to deconflict.
For aircraft vs mower (and this happens WAY too much and is usually fatal for the schmuck on the mower) we have 91.13
From another perspective the burdened (or give way) vehicle is usually the more maneuverable, or the one in a position with more maneuvering options.
Then there is common sense of course and even common courtesy which may or may not be as common as it is expected.