Given the general lack of government oversight in the Outworlds Alliance, and how much of the local economies work on barter, I'd not be surprised to find that the early population numbers are a reflection of the number of people bothering to complete a census or tax return out of the actual overall population, revised down further by ComStar's vested interest in making everyone think the Periphery is a desolate barbaric wilderness and that you should all be happier working in the Inner Sphere on worlds with a benevolent phone company nearby to offer divine guidance.