Which ethic?

7953227784So,  I am engaging in a business transaction in the Cape Town market today and find myself befuddled… Why is it that I must extend grace to a service provider that repeatedly fails to complete the job I have paid for and then pleads for a (false-)positive performance evaluation?  For sure, the market place is not a place where strict justice reigns under all circumstances and in all business deals.  I can accept that mistakes happen because we are human.  But surely there must be a level of accountability for poor service?  If our marketplace operated on the basis of unconditional grace then our economy would flounder.  Shouldn’t the market place be governed by the general principles of reward and retribution revealed to us in the natural order of the world around us?  Shouldn’t good work ordinarily be rewarded and tardy performance censured?
It seems impossible to have an economy, let alone a broader public square, functioning on the basis of gospel-informed notions of grace and mercy.   Does this not run contrary to the ethic of proportionate justice revealed to all humanity under the Noahic covenant (in Genesis 9)?   Such a notion is also seems difficult to reconcile with the natural law ethic of general cause and effect set forth in the book of Proverbs.
What confuses matters further is that all too often we Christians withhold grace and mercy toward those who should get it: those within the church – as if the principle of secular justice governs the life of God’s covenant community.  It is interesting how some insist on getting a free pass time and time again when fudging their secular callings in the marketplace, while often times those same people won’t extend an inch of Christ’s forgiveness to the personal failures of fellow Christians for the sake of peace, unity and love in the Church.