Heresy! If I mash the A button, surely my poke ball will not fail!!
In all reality though, with a cast of several dozen civs, the number of games you’d have to play to start seeing the uniform distribution come out is quite large. Even random chance allows for some civs to be significantly more common than normal in a sample of a dozen or two games.
Tack on that if we see Shaka we recall we saw him last game; but our brain doesn’t recall that we didn’t see him the game before that, and you have a self fulfilling prophecy.
that said, it IS possible for certain civ combos to actually be more common to be your neighbor conditional on them being in the game. For example, because maps are laid out with a hot equator and cold poles, if you frequently play civs which would spawn in tundra adjacent climates then you’re much more likely to neighbor Russia or Canada (the only civs with tundra bias) when those civs are in the game. Mountains tend to be paired with hills and if you play only Inca you’ll probably see more Greek neighbors than normal.