This proves my point being no matter what you are born as, you lack a lot of life options in Thedas. Even being a Grey Warden recruit ends with being 'join or die.'
Commoners can only move up in the world by marrying nobles, who in turn are only interested in other nobles to expand their personal fortune. Elves as a whole are bottom dwellers either in skid row, or as nomads.
Tevintir seems to be a ruthless but opportunistic land, at the very least.
In the case of the Grey Wardens, we are talking about an order of warriors who swear oaths of fealty. Although they can conscript whoever they want, I think that this is mainly used to get people out of situations like prison, the Circle, the Templars, etc... I don't remember any times when the Wardens actively forced someone to join. As far as the "or die" part goes, the Wardens do not force anyone to join on penalty of death... if we're talking about Jory, you can ask Duncan about that and he says that he did what he had to because Jory pulled a blade on him (which he did). There is no oppression or forced conscription on the part of the Grey Wardens...
The problem with the overall argument, however, is that it ignores freedom that goes beyond social class. A random qunari may be chosen to be an Arvaraad based on some qualifications their superiors believe they possess. Their options are to succeed within that role, die, or attempt to flee and then die or become lobotomized. A random human peasant can become a farmer, a merchant, a blacksmith, a tailor, or whatever else they want, within reason... Obviously they aren't going to become nobles through hard work, but this doesn't mean that the system is on par with heavy restrictions enforced by the Qun.