Control panels are a part of industrial automation. It contains many DIN standard instruments both in the front panel and inside back rails along with the wiring. They are called panel mounting and rail mounting. Cable management is a Science in these equipment.
Just like rackmounts hold big instruments or computers, control panels small or big have to hold DIN Instruments, switches and annunciators to make it easy for the operator. The maintenance work also is simple from the backside. It can be kept near the machinery which it controls
Some Control panels go into Control Rooms at a distance away or at a greater height from the shop floor. This way they can monitor and give instructions while managing a larger process like processing of chemicals and at the same time safeguarding the instrumentation and computers with controlled environments.
Some example circuits of panels here Electrical Control Panel Wiring