Predictability is there because combustion engines operate the same regardless of weather conditions.
AC / energy consumption anxiety doesn't exist because of said predictability as well as your ability to refill 1000km worth of fuel in a couple minutes.
The only difference if ICE were 100% efficient would be a slightly smaller gas tank.
This same reasoning should also apply to charging your phone, cranking the bass, etc, because that represents an additional load on the alternator which must be powered by the engine.
Of course, turning on the heater in gas vs electric car is a different story, because the gas car is using the heat energy you mentioned that would otherwise be wasted.
So yeah -- if your drivetrain is getting 131 MPG, your A/C that consumes the same amount of power is going to have a much larger proportional impact.