i've cut thread on steerers like this before at my shop, not in years though(coz of aheadsets) i don't think many shops have cutting tools these days, not sure how much we'd charge but we always carefully clamped the forks in a vice with some custom made fork clamps so as not to damage anything then tap the thread with the appropriate tool. obviously this was on steel steerers though.
i think whether or not shops carry these tools depends on how long they've been in business but also the staff or owners background, both myself and the shop owner have engineering backgrounds which make threadcutting and lathing/machining and problem solving something we can do as part of the normal day.
i've seen inside some workshops in other stores and seen not much more than allen keys, spanners, screwdrivers and hammers, oh and a chisel for removing headset cups! :shock:
right tool for the right job, a good mechanic will know this, and good shops will invest in tools to do things professionally.
