Why is an inductive load presented as a resistor on schematic diagrams?
I'm quite certain there is no established convention to draw inductive loads as resistors. That doesn't mean you won't find examples of laziness or errors.

I have seen schematics drawn like this:







simulate this circuit &ndash; Schematic created using CircuitLab

While some styles of schematic draw all resistors as rectangles, another style is to draw resistors as zig-zag lines like R1 above. The rectangle style is then used for things which are either some unknown load (perhaps an external device) or some potentially complex impedance which might represent some more complicated assembly when the particulars of that assembly aren't especially relevant to the point at hand.