People usually underestimate how difficult it is to do experiments, especially when you want to get quantitatively consistent results. Physics experiments sound easier than human experiments, but if you really do it and be serious with the numbers, you will find even high school physics experiments are really hard. For example, try to confirm F=ma, or measure local gravity to the third digit.
That doesn't seem particularly terrible in comparison to scientific reproducibility in other fields. What am I missing? https://en.wikipedia.org/wiki/Replication_crisis