I have a hard time grasping gamblers fallacy. When you flip a coin 100 times and it shows heads, flipping it again results always in a 50-50 chance for heads an tails. That is kind of logical, because past events cannot influence current outcomes. Furthermore, you don't know how the coin was flipped before the start of your experiment. It could have shown 300 heads in a row, which again would not have any influence on the current outcome. If it were this way, possibility as we know it can not exist (every coin would be 'rigged' in the sense that all past flips had to be accounted for).
Now comes the part where I'm struggling: In some professions, there are 2 negative Covid tests required. But when i take one test and it's negative, why does the second test matter? Shouldn't it be also the same possibility as when I took the first test?