The bridge problem

Today are 30 years since Berlin Wall fell and I want to describe how over control can harm.
Let's imagine that we have a capital city connected to the agricultural area via a bridge.
Over the bridge passes all kind of lorries with wheat, vegetables, milk which feed the capital.
The bridge is strategic if it is blown up,the people from city will starve.
Government decides that the bridge should be guarded by soldiers.
One guy from military ask himself what if inside the lorry we have a device that can blow up the bridge ?
So it is decided that each lorry should be stopped and searched.
Of course this leads to delays in supplying the city, tomatoes are getting rotten, the milk is getting sour. The farmers are not willing to bother with bridge checks and they don't sell anymore to the city.
The city population is starving, is rioting and it is overthrowing the government.
This is the reason why communism fell: centralisation and police control.
The police has the ultimate word. Safety of the regime and not development was the main focus.