That makes a huge difference historically, as it was pretty much only the UK who ever had appliances sold without plugs as standard. There were two reasons for this, one being a consequence of another.
Initially, the UK had no standardization of plugs and wall sockets - until the 1940s, there were 2 different types of 2-pin plug and 3 different types of 3-pin plug, all of them round-pin, unfused, and each requiring their own size of socket. There was also another type of plug which allowed appliances to be connected to a light socket. Most homes had a mixture of all types of socket, but not always in the same room.
Therefore, any plug fitted to a new appliance by the manufacturer had a very good chance of not fitting into the socket of the customer, and added to which, even if it worked in one room, it may not have fitted the socket in another. Adaptors to overcome this (and to allow multiple appliances to be plugged in all at once) were everywhere.
In the 1940s, standardization began, with the arrival of the 3-pin fused plug, which had rectangular pins and a range of standards within the design which made it safer than ever. However, the plug itself was not inexpensive, and the culture of selling appliances without plugs continued, as it saved a lot of money on the cost of the plug and the labour fitting it, reducing the retail price of the appliance.
During the 1970s, it became increasingly popular for large appliances (such as kitchen appliances) to be supplied with plugs attached, similarly for high-end appliances such as vacuum cleaners from Miele and Vax (who initially sold a very expensive carpet cleaning system, unlike the cheap crap they peddle today). Also appliances that were exclusive to the Electricity Board showrooms had plugs, and some retailers who thought they were a cut above would too - I know Marks & Spencer table lamps had plugs fitted to them while British Home Stores didn't (although like so many retailers, they'd cheerfully sell you a new plug).
All this changed in 1995, after it was considered too many people were blowing themselves up when fitting plugs in a haphazard way, and from thereon in, all new appliances had to have factory fitted plugs as standard.