Why are washers and dryers seperate appliances?

They already have those in the UK, but someone who has one told me they don't dry the clothes very well. I'm not mechanically inclined at all, so I don't know what exactly the problem is, but they did tell me they don't work as efficiently to dry as a separate tumble dryer does.

*edited to say - you can find reviews of specific washer/dryer units here:
http://www.which.co.uk/reviews/washer-dryers/aeg-electrolux-l12710vit/review

I have seen the two connected into one vertical unit. Tough to carry to the repair shop if one breaks down. Anyway, some people only want to pay for the washer. We still have clothes lines, though we now tend to call them solar powered driers.

From a design point of view, washers are simple devices and dryers are simple devices, but putting them together makes for one very complicated device. In the case of an electric dryer, you have to design a device that uses water and also uses electric coils. Lots of opportunities for bad things to happen.

Wouldn't be time efficient either.

Don't you wash the 2nd load while the first is drying?

Chai(let's see what am I going to wear tomorrow so I'll make sure they're in the same load)Tea

Here is a review of washer-dryer combos
http://www.consumersearch.com/washer-dryers/review

My Mom has one from Miele and very happy with it. She doesn't have
space for both so the next best thing is a combo.

Several reasons:

There are people who don't want dryers because the clothes dryer is the biggest energy consumer in the house.

And, even if someone uses a dryer, not everything should be machine dried. I would never dry socks in a dryer.

And, if you want to do more than one load at a time, having to use the same machine for two tasks means the work will take twice as long.

Finally, most dual purpose appliances don't work well and, generally, it seems that one function always breaks before the complete appliance dies. Remember the tv-vcr combo? The vcr always broke before the tv. I have a boom box in my kitchen and the cats knocked it over. The radio is still fine but the CD player isn't.