the UK power grid is weird. mostly due to echoes of the war. used to be that, to save copper, the entire house and sometimes multiple houses on a street would be wired as one big loop of wire, no fuse box or anything. that's where the individually fused plugs and switched sockets come from. then, since it turned out to be quite a good idea for safety, they kept doing it.

So we can turn the power on and off.

Why else would you have a switch next to a power socket?

To turn them on and off.

This is virtually standard in Australia

I like them, personally. You don't have to use them but they are sometimes handy. I just spent 30 seconds feeling around a TV to turn it off only to discover it doesn't have buttons. Killed it at the wall.

It's not a deal breaker, in any case. The weird foreign convention I would like to shame is doors that require a key to open from the inside.

Americans don't have this???

Safety, easier to switch things off without unplugging them. Why not have one if it's more convenient? Not all of them have switches though.

Kind of off topic, but I've just gotta add that the safety shutters over the positive and negative terminals that only open when the ground pin (which is longer than the others on the plug) is inserted up top is brilliant, it basically makes short circuiting impossible. Electrical outlet design is one of the few things I'll concede the UK does better than the rest of the world.

UK household electricity is pretty spicy compared to many other places - it has more safety features as a result. (3 pinned fused plug, socket switches etc)

Great for turning off a device or several devices without having to unplug (e.g. if the sockets are behind a bookcase, this is much more convenient). Not a super common need but when it saves moving furniture it helps. Given that UK switches are tougher to plug in and unplug than most (due to safety features), I prefer using a switch. Also, the switches are cheap and give more options, so may as well!

I rely on one for a light where the switch broke and wasn't easily replaceable, so being able to fall back on the mains switch meant I can keep using the light.

I present to you my favorite YouTube person:

The GFCI/RCD, a simple but life saving protector:

https://youtu.be/ILBjnZq0n8s?list=PLv0jwu7G_DFU62mIGZNag5vQ0a6tDGBpO

In defense of the Switched Outlet:

https://youtu.be/2DGqVbTHX-k

Electrical topics playlist:

https://youtube.com/playlist?list=PLv0jwu7G_DFU62mIGZNag5vQ0a6tDGBpO

I could just watch this guy all day lol

I like the integration of the switch, should be standard. I use many switch plug-ins just to avoid stand-by consumption (it really adds up over the year) and to avoid high pitch humming on some devices.

YSK: there's also remote controls for these switches, very handy

As any cautious parent could tell you, these are helpful when the toddler starts sticking things in places where they don't belong. Such as metal cutlery. In the power sockets.

"so many"?

isn't it all of them?

Being a uk person its cause they can & its also in to building / electric code. Its just a switch that breaks the live leg, stops sparking when plugging in stuff.

Everything you'd want to know about British wiring and my introduction to Tom Scott:

https://youtu.be/UEfP1OKKz_Q

No one seemed to mention the important fact that UK and I think most Europe is a higher voltage than the US. Tom Scott as well as Technology Connections have some good videos on the whys and differences it causes.

Safety and convenience versus the cost of including them, I expect.

The Wikipedia page for BS 1363 says they're optional and weren't added to the standard until 1967. I can't recall having seen a domestic socket without one.

But it seems the only legal way to read the actual standard is to pay for it, and even the HSE website isn't much help.