In my sci-fi world, mankind has begun colonization of the large asteroid Ceres. There are several established towns on the surface, but most of the population live underground in icy/rocky caves. The major industry is mining and exporting water-ice. Ceres is undergoing a rapid transformation from primitive mining backwater into a trade and refueling hub. It's becoming a focus point for belt mining, and a major supplier of water-ice and precious metals as mankind starts to explore the rest of the solar system. There are a few orbital fuel depots and repair facilities now, and large trading ships come and go frequently. Many see a chance to make their fortune by going to Ceres for a few years to try to strike it rich.
My story follows a pilot, who does short surface to orbit flights. He's a delivery boy basically. He's poor, with little opportunities, stuck in a dead-end job, working long hours for crappy pay, and he's doing it in a leaky, worn-out ship held together with duct tape. I am really trying for a realistic feel to everything, with one concession for style: I love retro tech! I want the spaceship cockpits to be filled with switches and levers, analog dials, and gauges, and I want to avoid computers, holograms, and anything high tech as much as possible. The ship is cobbled together from spare parts and ingenuity. Higher tech equipment can and do exist in my world, but just not on-board my protagonists spaceship.
How can I explain the lack of more modern, convenient technology? I want to focus on astro-navigation, where my protagonist flies with the use of a sextant, stopwatch, observations, and maybe a primitive computer to do basic orbital mechanics calculations. It's all seat-of-the-pants flying experience. A GPS satellite system seems likely and economically possible to build around Ceres at this point, but how do I explain that my pilot doesn't have a GPS receiver on board, or a laptop or tablet computer capable of drawing 3d orbital paths even? I wish to keep the description of the pilot character to an absolute neutral minimum, so no weird religious beliefs. He's an average Joe in all ways.
A good answer to this question will explain and support my stylistic decision to only have primitive mechanical instrumentation available on the protagonists spacecraft (think 1960s space tech level) in an otherwise future sci-fi scenario. Radio receivers are ok, as are radar and the kinds of instruments you'd find in a light aircraft cockpit, but I need a way to explain the absence of computers and screens. These things would likely be affordable even for the most humble of vehicles. So why are they not available here?