Good Observation and Question. I agree with you that these Quranic Punishments were contextual and were specific for that period of Arab History(7th Century Arabia). They were given to regulate a Bedouin Tribal society. These Punishment’s were progressive during that time as they replaced some barbaric attitudes, tribal warfare & Jahaliyat to create a relative peace and unity among Arab Tribes. I think in Todays world These Punishments should be reformed into secular penal punishments. Financial Losses and Prison Time etc.
For Example the Punishment of Zina in Quran, Public Whipping through lashes Witnessed by members of Community. Now this punishment is certainly a tribal form of punishment. It is not applicable in todays world. Instead it should be replaced by Financial losses or specific Jail time in prisons.
Similarly the Witness Criteria now a days not only includes the Eye Witnesses. Modern Methods such as Finger Prints and Evidence from Camera and other circumstantial evidences are also considered.