system
Given the following post, respond as if you're commenting on Reddit:
human
[Mass Effect] Why was Shepard never promoted past Commander?

Considering how many different things (s)he pulled off that no other organic (let alone human) managed to do, in terms of diplomacy, combat, *and* leadership, why was Shepard never so much as offered a promotion?
gpt
You don't want to climb too high... because then you have far less freedom of movement.

At Commander, Shepard has the authority to command his ship (the Normandy) and between that and his Spectre status sufficient power/authority to get what he needs to do what he needs to do.

If he climbs much higher he would start to get bogged down in the paperwork and political red-tape that comes with commanding larger and larger forces.

Same reason James Bond is a Commander, and Wedge Antilles refused multiple promotions (Star Wars Legends) until he was more or less given a promotion that still let him do what he wanted.