I have always found that Nokia heavy subsidise their phones here.
Which means that most people walking into a phone store and asking the rep's advise will be pushed towards a Nokia. They usually have one of these at home.
Also, Nokia always have the latest technolgies on the devices. The Nokia OS may be flakey, but a lot of people are convinced by the features and the salesperon's pitch.
Show them that HTC's 3megapixel camera will take a better picture than the N95's 5megapixels, that the battery life is so much better and that a Windows Mobile can be charged from a PC and they'll see that they chose the wrong phone.
Getting a commission paid salesperson to promote the better device will never happen...