I think one of the key reasons is that scientific effort and attention is spread over the largest possible space, in order to make good use of grants and brains

I think one of the key reasons is that scientific effort and attention is spread over the largest possible space, in order to make good use of grants and brains, most people work on different topics, and are not intimately familiar with the work everyone else to develop a 'smell' for doctored results. In contrast Speedrunners are working on the same problem, and are intimately familiar with the details of their chosen games, are aware of all the tips and techniques one could use to get ahead, and if someone suspiciously pulls ahead of the pack, you bet they will analyze everything to the smallest minutiae.