The answer is as cruel as the situation. You need to lace your shoes only so that the laces carry the weight of the shoe, plus a bit of extra force when you are

The answer is as cruel as the situation. You need to lace your shoes only so that the laces carry the weight of the shoe, plus a bit of extra force when you are running. That force is mass of the shoe, times acceleration, so it is only a little extra force, compared to their weight. If you are hit by a car, your body is subject to extreme accelerations, many many times more than the normal gravity. You can observe that when you watch videos from crash tests. And these G forces slip off the shoes.