I can not find any information about the type of load of neon lamps, for example neon probe or wall contact plug or extension cord with switch with small red lamp. I think this is a passive capacitive load, but in the workplace we measured an extension cord and the meter showed it is a purely active load. How does it work?
A neon indicator consists of a small neon lamp in series with a suitable resistor. The resistor will be around 330k ohms for 230VAC, and lower for 120V.
When fed with an AC waveform, between 0V and 90V, the neon will not strike, and is effectively open circuit. Above that voltage, the neon strikes, and its resistance rapidly drops. At that point, the resistor limits the current. As the AC voltage drops again, the neon will remain lit down to quite a low voltage, at which point it goes out.
Overall, it will look like a resistive load, dominated by the resistor chosen.