The goal of a campaign is for everyone to have fun. It's not a contract, it's not adversarial, and it's not going to work if you treat it as such.
Compromising so that everyone can enjoy the result is just normal behavior -- nothing game-specific about it. Yo talk it over and decide what will work for everyone. The GM has exactly the same priority as anyone else. Like everyone else, she expects to have fun playing and shouldn't have any burden on her to play a way that will make her not have fun. Like everyone else she should compromise to help others have fun.
If you have a GM who cannot have fun running a campaign with an elf in it, and you have a player who cannot have fun without playing an elf then:
- This is a sad state of affairs for adults to be in.
- You will not be playing together
Should you make accommodations to one player and not others? Of course! If a player always plays elves, loves elves and really wants to play an elf, then the GM should try and accommodate that. It doesn't then meant that everyone then has a free "I get a special thing" card. If there's something someone else wants that would make them super-excited, sure, try and work it in, but it's not a legal "everyone gets one exception" thing.
If I'm cooking a dinner and I plan for Indian food, and someone says that they are allergic to cardoon and will die if they eat it, then obviously I'm not going to use cardomon. If they say they cannot eat cumin, then I might just abandon plans to cook Indian because I cannot imagine trying to cook that way (it would be no fun for me). If someone says they absolutely love chocolate cake and would really love to have some, then sure, I'll add one to the menu, if it means that much to them, because it doesn't lower my fun much and it means a lot to them.
TLDR: Be excellent to one another