Discussion on reverse Income disparity among formal and informal sector

In India. Let me give you an observation I see in my city. A clerk gets Rs 25000 per month salary. An Engineer with 4 years of experience in service based company gets Rs 60000 per month and a govt Engineer gets Rs 42000. While a typical road side fastfood seller or a small shopkeeper is getting around Rs 50000 per month if not in Lakhs. Why did this income disparity come? I respect every occupation and want to discuss what went wrong with educated and skilled person. Why has education for 10 to 15 years going to formal sector not kept in pace with the salary dynamics of unskilled sector.