The hood should be wired to a fused spur unit that is located near by. The wiring can be done so that none of it is visible. That plug and socket set up is very crude and ugly.
Your oven and hob are supposed to be connected to a cooker control switch on a dedicated circuit via a hardwired connection. They should NEVER be connected via a plug and socket.
I have a basic gas stove which has the sparker (to light the gas) connected to a standard plug and socket behind it. The extractor hood (light and fan) also run off a plug. Though hidden behind the oven it's not very neat (and have inherited this state of affairs from previous owner) but your post implies this is possibly dangerous. How and why so?
I understand why an electric oven needs its own circuit, etc, but not sure what you're getting at here...
Edit: Sorry, just seen this a bit later on...
Agree about the hood - it needs to be on a fused spur or on the lighting circuit(?)
Re the cooker not necessarily true - it depends on the oven and hob - many supplied now (with 'eco-friendly' energy ratings) specify connection using a 13amp plug to a socket on the ring - you can still connect to a cooker feed if you wish but it is not necessary.