This makes me wonder, if we were in a universe exactly like this one, except that the laws of physics specified everything exactly, and it matching this universe was a total coincidence, would people have subjective experience?

The problem here is the 'total coincidence'. This is analogous to watching a video of someone being tortured that was randomly generated. No one is being harmed and it only seems like it because of a massive coincidence. There is still enough data to specify the brain state it your scenario so, given our current knowledge about the brain, it is more likely to have conscious experience than the videotape one. Even with the naive concept of time, it would be very hard to define what constitutes a calculation, and it looks even harder without one.