Modern designs of land vehicles chassis have undergone so many changes that a reference to a "frame" is no longer meaningful. In many instances the old, side-rail, cross-member, front and rear axle construction is no longer used. Uni-body construction, where the "floor pan" of the body becomes the wheel controlling platform is one example. Four wheel independent suspension (i.e., no axles) is another example, and front wheel drives, where the driving mechanism is encased within the cross-member, makes it virtually impossible to obtain reference points on the front "axle".
"Wide track" tread width on one pair of wheels and cases where one frame side rail is "offset" at the rear to make room for the engine, further complicates the matter.
Reducing the problem to basics, one major fact evolves. Regardless of the existence or absence of a "frame", front or rear axle, front or rear drive, standard or "wide track" -- the various wheel control (i.e., as to relationship) materials are formed, cast, or forged to ultimately obtain the proper wheel position (i.e., not the alignment of two opposing wheels, but the plane position of four wheels). This is separate and apart from camber, caster and toe.
With the appearance of the "wide track" vehicle, the term "tracking" is no longer meaningful (i.e., the term originally posed the question, "do the rear wheels follow in the tracks of the front wheels?"). Obviously, the "wide track" on one pair of wheels prohibits "tracking".
A more descriptive term might be "parallel test" as this, is reality, is what must be tested (i.e., the parallel relationship of the four wheels in the horizontal plane, plus their vertical contact point on the road while the front wheels are "squared" to a line drawn transversely through their steering axes). This position is automatic when setting toe with applicant's wheel aligner, described in U.S. Pat. No. 3,455,936.