Quote Originally Posted by yukonhorror View Post
... non-universal access to space travel (too many planet systems with similar levels of technology).
If traveling to another star system is as easy as a ride on a jet today, or even as easy as a 17th century ship voyage, technology will transfer relatively quickly to all worlds on standard routes. (A thumb-drive, or its ultra-tech equivalent, has negligible mass.) Star Wars, for example, implied that ships regularly carried goods to Tatooine, surely a Force-forsaken hellhole if there ever was one.

However, consider all conditions where even technology transfer becomes far less likely:
  • Some worlds are seldom if ever visited by starships after initial settlement. Maybe initial colonization used generation ships, the mysterious Ancients seeded humans all over the galaxy, or the non-human(?) natives evolved on that planet.
  • Interstellar travel is perilous, expensive, time consuming, or otherwise uncommon. For example, FTL travel and communication are impossible, so that colonies 100 LY away will always remain over a century out of date.
  • Most planets lack the industrial base to replicate high-technology items, even if they get plans from the next passing ship or over the FTL telegraph.
  • FTL travel is only possible/likely between certain points in space, leaving worlds without a jump gate to fend for themselves.
  • FTL is a closely guarded secret, rare gift, or technology wholly under alien control. (Mi-Go brain cylinders, anybody?)

Possibly, also, some technologies progress faster in some cultures than others. Even in our planet, the Mayans invented wheels but used them only for toys because their mountainous terrain precluded smooth roads. So, for example, one planet far advanced in biotechnology invents bio-ships ahead of anyone else ... armed with missiles and rail guns, since their physicists never discovered principles required to build disruptors.