Also, HTC are not the only ones using servers, so if they care or doesn't about OS prices, doesn't matter at all. Industry in general cares about cost/benefits ratio. OS prices might be a negligible difference and thus be ignores completely. Employing costs are usually important, so the fact about being easier to find a Linux admin still matters most of the time.
Originally posted by OpenSLOWlaris
Specially when there are two options with advantages and drawbacks, a lot of people will agree one or the other is better, mostly because it fits better their needs.