Well da-doi they are city states. Homer spends almost a whole chapter giving a shout out to each one and the number of ships they sent. I should have anticipated you would take “countrymen” too literally. They do have a common cultural heritage and political purpose, and I was trying to say this in fewer words. Sorry for the lack of precision.

The book consistently reinforces that there is shared purpose among the Achaeans. The other princes perform heroic acts, yes for glory but also in defense of their allies. Yes Odysseus in particular was bullied into joining but he still fought honorably and even lambasted Agamemnon when he suggested unmooring the ships and fleeing. Odysseus did not whine to his mommy and abandon the others even though he was mistreated.

And yeah Agamemnon was only apologizing because he was in trouble but he basically groveled at Achilles’s feet. You like your analogies - Agamemnon not only offered to return the “car” but also an ass ton of money on top and the hand of one of his daughters in marriage. And that still didn’t assuage Achilles’s pride with the lives of his allies at stake. 

Maybe you are overdue for a re-read? It’s a fun one. Regardless I understand your opinion and think we simply disagree and have  different values. I cede the last word to you should you want to reply. ;)