Taco trucks have been a mainstay of Los Angeles foodstuffs for a long time before the current trend of 'gourmet' truck food started. I'm not sure if the mobile/car-centric nature of the city tends to endear us to a mobile food cooking service or what; the 'food truck' craze has been very poopular here.
Since buying/leasing a physical location is such a costly and risky venture, these trucks have been a great way for budding restaurateurs to get their feet in the door; see what works, what doesn't and perhaps eventually open a physical location. People get experience doing something they love and building a business, people get fed with interesting food that would be prohibitively expensive or otherwise difficult to discover (due to culinary fusion or other reasons), and the city gets tax revenue.
Since buying/leasing a physical location is such a costly and risky venture, these trucks have been a great way for budding restaurateurs to get their feet in the door; see what works, what doesn't and perhaps eventually open a physical location. People get experience doing something they love and building a business, people get fed with interesting food that would be prohibitively expensive or otherwise difficult to discover (due to culinary fusion or other reasons), and the city gets tax revenue.
Win/Win in my book.