Fog lights are intended to be used primarily under foggy conditions (duh!). The AI appears unaware of this piece of "ancient wisdom".
Identified causes and resolution progress
Unlike the real world where (the likelihood of) fog formation depends on (among other things) humidity and temperature, in OMSI it solely depends on the value of the visibility weather setting. Sadly, that very value is not communicated to scripts. And since that value neither significantly affects, nor is affected by other weather-related settings that scripts have access to, scripts can in no way reliably "detect" fog. Surely, vehicles could act as if certain ranges of temperature and humidity implied foggy conditions, but it is trivial to see that the user would in no way be obliged to select temperature and humidity values that justify their selected visibility.
The current workaround (see definition of "adverse-seeing conditions" in readme) is to use fog lights primarily when the environment is both dark and wet (e.g. overcast + low brightness + intense precipitation).
User-level workarounds
If you'd like to see more vehicles employing fog lights, adjust your time / weather settings such that the environment is both dark and significantly wet (rainy or snowy).
Symptoms
Fog lights are intended to be used primarily under foggy conditions (duh!). The AI appears unaware of this piece of "ancient wisdom".
Identified causes and resolution progress
Unlike the real world where (the likelihood of) fog formation depends on (among other things) humidity and temperature, in OMSI it solely depends on the value of the visibility weather setting. Sadly, that very value is not communicated to scripts. And since that value neither significantly affects, nor is affected by other weather-related settings that scripts have access to, scripts can in no way reliably "detect" fog. Surely, vehicles could act as if certain ranges of temperature and humidity implied foggy conditions, but it is trivial to see that the user would in no way be obliged to select temperature and humidity values that justify their selected visibility.
The current workaround (see definition of "adverse-seeing conditions" in readme) is to use fog lights primarily when the environment is both dark and wet (e.g. overcast + low brightness + intense precipitation).
User-level workarounds
If you'd like to see more vehicles employing fog lights, adjust your time / weather settings such that the environment is both dark and significantly wet (rainy or snowy).