All of electronics assumes Kirchhoff's Current Law and Kirchoff's Voltage law, which does not truly exist in reality. Electrons often escape a circuit (see antennas, which throw the voltage / current into a wave that is emitted out of your designs). All wires are antennas, so even the most basic circuit doesn't have all the current return in a loop.

The assumptions of KVL and KCL are just over-simplifications of true physics, Maxwell's equations. Because working with Maxwell's equations directly is too much effort in practice.

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Electronics itself is a huge abstraction upon physics. You could, in theory, calculate all the voltages and currents using Maxwell's equations, except this isn't useful at all.

Similarly: most of "Analog Electronics" uses simplifications as well: OpAmps are often assumed to be ideal (aka: infinite gain), which is good enough in most cases.