"One example we use is the No.3 Memory of Lenin Tractor Repair Factory in Zhuhai, which already in 1973 had started repairing tractors outside the plan. It would take tractors that needed to be repaired from other units, repair them on the side of the plan, and then get payment in kind. That payment in kind was then either bartered further within Guangdong, or smuggled downriver to Hong Kong. By 1973 this unit had a Hong Kong bank account. If this had been discovered at the central level, these people would have been shot."
Turning Shenzhen from an off-limits border area into a special economic zone made it easy for those businesses to go legit and grow, but they were already waiting in the shadows to seize that opportunity.
There are a few more SEZs https://en.wikipedia.org/wiki/Special_economic_zones_of_Chin... but none did as well as Shenzhen, probably because of location factors.
If the government plans to try free-market capitalism then I'm in favour of the plan.