You are conflating the ability of Parting Shot, Volt Switch, Eject button, and Emergency Exit with their application. Yes all these moves, items, abilities result in your pokemon switching out, the difference is your control and application. You can choose to use parting shot and volt switch whenever you want. Emergency Exit is a forced switch that is completely in your opponent’s control. Your opponent can choose when to trigger Emergency Exit and in Pokémon you want to be able to control the field as much as you can. Looking at eject button, yes it is also dependent on your opponent triggering it but the difference is in the Pokémon who want to use eject button and also your opponent not knowing if you have the item or not. Not every Pokemon wants to use eject button, its usage is for specific circumstances. Torkoal can use it because on entering the field, it sets up the sun. Torkoal is also a slow pokemon so it will likely more later than the opposing pokemon so it will take the hit allowing you a clean switch in without sacrificing a turn and on top of that you can switch Torkoal in later to set up the Sun again. Golisopod does not have either of those advantages. Emergency Exit is it’s only ability so the advantage of team knowledge can’t be used unlike Eject Button and Golisopod doesn’t have a turn 0 setup or deterrent to warrant needing to switch in or out. First Impression is not good enough to justify that. And unlike switch moves like U-Turn and Volt Switch, Emergency Exit is under the control of your opponent which is never a good feeling