Over here it is only the outside that is done as a matter of course, it seems that window cleaning over here differs quite markedely from that in the States.
Here, house domestic window cleaning is carried out monthly on domestic work.
In the States, from what others from across the pond have told us, window cleaning is carried out just a couple of times a year, and everything is done; outside, inside, screens and all parts of the frames, therefore making it an altogether bigger operation.
Over here the average house is done and dusted in 20 minutes, and I would reckon that across the board the charge for that would be around £7 or £8.
That isn't to say that people don't have their insides cleaned, many do, but more often than not it is a separate request, so yes, the insides of windows are done on domestics, but not often (by and large that is!)
Ian