One very practical reason that comes to mind is waterproofing. Kitchen counters get wet, and office desks do not. Anything with a plug is at greater risk of shorting.

I’m a big fan of this notion. My hot water dispenser has a magnetic power dongle kinda like macbooks MagSafe, but bulkier [0]. Ideally something like that would be more standardized across appliances the way some of the other three prong power cords are.

[0]: https://youtu.be/E2WrHHRYrV4?t=108

Erm, let's not.

Take one look at the mess of incompatible detachable cords that come with LED lighting fixtures from China to see what results.

They could have used bog standard IEC 320-C5 cables, but they didn't. Why? Because they wanted to cheap out on the conductor AWG and IEC 320-C5 is quite specific about the conductor gauges and current capacities.

So, the LED lighting manufacturers produced a bunch of cables that are in almost exactly the same shape and size factor as IEC 320-C5 while being just enough incompatible to not invoke the certifying authorities--all to save a couple pennies in copper.

Regulations make detachable cords of electric kitchen appliances hard.

Most need double isolation and water-proofing, hence not detachable.

It could probably be done, but it likely needs a different type of connector, akin to M12/M8

The plug between the cord and the device must be sturdy and meet regulatory standards

So it is expensive

It is cheaper to just attach the cord

That is the reason