I would guess it's more real estate. Between South Draper and Lehi there is tons of room for new construction (especially now that the prison is moving). There has been a huge amount of office construction there over the last ten years and continuing today. Office space in SLC proper has to cost a fortune by comparison. Building/renting there gives you good geographic positioning to attract employees from both the SLC valley (about one million people) and the Utah county valley (about 500,000 people).