Non-equilibrium electronic processes are widespread in semiconductor devices, coherent quantum systems, optoelectronic conversion devices, and micro/nano thermal management. They are key physical processes that determine device performance and energy conversion efficiency. For a long time, non-equilibrium electron measurements have been closely linked to ultrafast time-resolved techniques. Femtosecond, picosecond, and even attosecond experiments have provided important experimental windows for problems such as electron relaxation, electron-phonon coupling, photogenerated carrier dynamics, and photoinduced phase transitions. However, electronic systems in real-world devices do not always exhibit transient relaxation after a single external excitation, but rather are more often in a steady-state non-equilibrium state driven by continuous bias, current, illumination, or temperature differences. In this case, the core issue is not just how electrons recover equilibrium over time, but how they acquire, carry, and ultimately release energy within the device. This paper first distinguishes between equilibrium, transient non-equilibrium, and steady-state non-equilibrium states based on the macroscopic budgetary relationships of general open systems. Then, it outlines typical ultrafast electron dynamics measurement methods and their applicable boundaries. Furthermore, it discusses the value and limitations of steady-state non-equilibrium electron measurements in working devices from three levels: port transport measurement, high spatial resolution nanoimaging, and non-equilibrium electron energy transfer. Building upon this foundation, this paper discusses the significance of passive infrared near-field imaging methods such as scanning noise microscope (SNoiM). SNoiM utilizes the evanescent electromagnetic field generated by thermal fluctuations or non-equilibrium current fluctuations in the sample. A metal nanoprobe scatters the local near-field signal to the far field, which is then read out by a highly sensitive detector, thereby imaging the hot electron fluctuations and non-equilibrium electron energy distribution in the working device at the nanoscale. This paper points out that while non-equilibrium electron measurement is developing towards higher temporal and spatial resolutions, it also needs to address real steady-state operating conditions and establish a new paradigm of infrared near-field super-resolution measurement that can directly observe the electron energy transport and dissipation paths inside the device.