"Fair wage" is a meaningless concept. If one person is willing to pay $X for a job and another person is willing to do it for that price, other people should butt out.
The problem is when there are confluences of conditions that systemically prevent someone (or their 'class') from having the mobility to exit their condition, even when they have enough merit to otherwise warrant it.
Take for example indentured servitude, or third world sweat shops. Sure, working for $0.28 a day in a (dangerous, unsanitary) factory is better than subsistence farming. But if this opportunity is enough to feed a family but not enough to lift the family from a condition whereby it can exit from needing to work in the factory, how is this so very different from perpetuated servitude?
Take serfs. While serfs were 'bound to the land', the condition of the serf was voluntary and mutually beneficial: Wikipedia reads "Serfs who occupied a plot of land were required to work for the Lord of the Manor who owned that land, and in return were entitled to protection, justice and the right to exploit certain fields within the manor to maintain their own subsistence."
Certainly it was a better deal for the serf to labor underneath a lord than live in the wild - especially since all fertile lands had already been captured by lords. And indeed, you see the language and argumentation during the time period repeat a variant of your argument: both the serf and the lord benefit from the situation and therefore it is good. Similarly, whites made similar arguments about black slavery throughout the history of American slave trade.
But a situation where both parties have no benefit by changing their 'local' stratety by small amounts represents a local Nash-like equilibria at the best - and not anything one could argue is a 'global' optimum. And in fact, if one truly buys that markets are meritocratic, one should be willing to subsidize the equality of opportunity so that as many people start off on an even footing as possible.
In sum this is to say that, like Braess's Paradox, locally rational decisions lead to local but not global maxima - whose gaps can be seen to be gigantic from history. When we discuss opportunities for labor, wealth and quality of life, this becomes an ethics question.
It is not so clear, at least to me, that the principle of trade (especially given its other major problems not covered here) should be prioritized over ethical considerations. Quandaries like this do lead us to ask what sorts of wages and opportunities are 'fair'.
The idea of mobility is a warping of the term 'fair'. It assumes the existence of a system in which people are poor and rich, it's a priori unfair, regardless of whether movements are possible.
I am (was...) working class. I had the 'merit' to rise.
Do you understand what that means?
It means that completely randomly I was blessed with a talent. I also put a bit of work in (the willpower to do so is arguably a talent in itself).
So I win (in a limited sense. I'm not really well off, just relatively). And my schoolfriends do not.
How is that 'fair'? How does that concept of merit make any sense at all? It may result in more efficient allocation of resources, but only within the current system that ensures most people have restricted autonomy. In a reasonable world the difference between a lower and higher paying job would be toys, not serfdom vs. fu money.
The issue is not individual decisions of how to allocate capital, about wages being 'low' or 'high'.
The issue is wealth and ownership and the huge differentials. Especially on basic necessities. Ownership is useful and probably something we desire, but the ability for groups to monopolise/oligopolise the necessities of life (e.g. land) and then use force to defend them against people who need them is broken.
Worker lives in a flat, landlord owns the flat, the landlord owns a fraction of the workers' labour. Why should they need supernormal amounts of merit in order to escape that situation? Why should they need to be above average in order to live the life they already do but with the exploitation removed? It makes no sense.
I come from a similar situation and these sorts of discussions always frustrate me. Hearing well-off middle class people, typically White, debate lower class struggles. I lived through this. All of my friends had the same opportunities. I’m not exceptionally talented, but I got out and they stayed in the ghetto. I graduated high school, they dropped out. They bought Nikes and Nintendos, I went to the public library.
Ultimately, from what I experienced growing up, the poor keep each other down. So while they chose friends, I chose solitude. Because “fitting in” meant remaining poor, choosing crime and materialism over education and grades.
I think what frustrates me is the idea of there even being a 'condition'.
It sort of makes sense globally. But in Western countries we can house everyone by just shuffling wealth about a bit, literally just writing words on paper. But we don't. To the rich money is a video game, to the poor it is a ball and chain...
