Each coin-toss is a deterministic physical process governed by laws of motion. If we had perfect information about the motion of all components in the system (hand, coin, air, floor, etc.), then we could, in principle, perfectly predict the outcome of every toss. Each individual toss would have a 100% probability of its predicted outcome.
Since we typically lack any of that information, we are stuck with the 50 / 50 prior distribution.
Since we typically lack any of that information, we are stuck with the 50 / 50 prior distribution.