I'll answer what seems to be the core of your question.
If a skilled labourer is being thankful to god for the opportunities he gave > him to acquire his skill - should the unemployed labourer complain to god for
treating him unfairly and not giving him opportunity?
A consistent theme in Christian thought is to always be thankful to God, in good times and in bad.
From the point of view of one Christian denomination, Catholic, misfortune and suffering are opportunities to get closer to God, and to let God lead us to a productive path in accord with His will. In the case you cite, the response recommended is to be thankful to God for providing another opportunity. The labourer is unemployed, so he embarks on a journey to find employment. The journey itself will reveal a variety of opportunities and graces if the Labourer trusts God and goes forth. (If all he does is sit around and complain that God didn't find him a job, how thankful is that?)
There's a longer discussion here based upon St Paul's letters and their treatment of suffering as a gift from God. A few points.
Pope John Paul II explains why St. Paul writes so much on suffering:
“The Apostle shares his own discovery and rejoices in it because of all those whom it can help – just as it helped him – to understand the salvific meaning of suffering” (Salvifici Doloris, 1).
Philippians 3:8-11 - Indeed I count everything as loss because of the surpassing worth of knowing Christ Jesus my Lord. For his sake I have suffered the loss of all things, and count them as refuse, in order that I may gain Christ and be found in him, not having a righteousness of my own, based on law, but that which is through faith in Christ, the righteousness from God depends that I may know him and the power of his resurrection, and may share his suffering, becoming like him in his death, that if possible I may attain the resurrection from the dead on faith;
2 Corinthians 12:7-10 - And to keep me from being too elated by the abundance of revelations, a thorn was given me in the flesh, a messenger of Satan, to harass me, to keep me from being too elated. Three times I besought the Lord about this, that it should leave me; but he said to me, ‘My grace is sufficient for you, for my power is made perfect in weakness.’ For the sake of Christ, then, I am content with weaknesses, insults, hardships, persecutions, and calamities; for when I am weak then I am strong”