The author supplies two further applications of a proxy.
Valid seclusion: in certain matrimonial rulings a legally qualified seclusion serves as a proxy where direct inquiry into the underlying event is impractical.
Travel: legally recognized travel provides a manageable basis for dispensations, even though actual hardship differs among travelers.
The examples depend on their legal conditions. Not every moment alone together is qualified seclusion, nor does every short trip meet the legal definition of travel.