my take on this: The high bias, low variance means that the models used in the book are the standard used in physic. The low variance means that the author does

my take on this: The high bias, low variance means that the models used in the book are the standard used in physic. The low variance means that the author doesn't use any artificial model or parameter except those that arise from physical considerations. Care is taken to motivate physically ML models and those far from physic can't be used with many parameters (hyperparameters).