  Kappa-distributed velocities in plasmas are common in a wide variety of
settings, from low-density to high-density plasmas. To date, they have been
found mainly in space plasmas, but are recently being considered also in the
modelling of laboratory plasmas. Despite being routinely employed, the origin
of the kappa distribution remains, to this day, unclear. For instance,
deviations from the Maxwell-Boltzmann distribution are sometimes regarded as a
signature of the non-additivity of the thermodynamic entropy, although there
are alternative frameworks such as superstatistics where such an assumption is
not needed. In this work we recover the kappa distribution for particle
velocities from the formalism of non-equilibrium steady-states, assuming only a
single requirement on the dependence between the kinetic energy of a test
particle and that of its immediate environment. Our results go beyond the
standard derivation based on superstatistics, as we do not require any
assumption about the existence of temperature or its statistical distribution,
instead obtaining them from the requirement on kinetic energies. All of this
suggests that this family of distributions may be more common than usually
assumed, widening its domain of application in particular to the description of
plasmas from fusion experiments. Furthermore, we show that a description of
kappa-distributed plasma is simpler in terms of features of the
superstatistical inverse temperature distribution rather than the traditional
parameters $\kappa$ and the thermal velocity $v_{\text{th}}$.
