This condition of newly sprouted beans shown in the pics is known as snake head or bald head...it happens when the bean seed is cracked when planted...or because the soil has crusted pulling the leaves off as the seedlings emerge...
Reasons for crusted soil is area has experienced moisture, and allowed to dry, or can be granular fertilizer applied close to, or on, the soil surface whick when exposed to moisture and allowed to dry can create a crusted soil...
Prevention is to plant crack free seed and/or keep soil moist at all times until germination is satisfactory...
In some instances, bean foliage may grow at the cost of slow growth, and possible reduced harvest...if a high percentage of this condition is experienced, it may be wise to replant...
In this photo, the seedlings to the right have experanced snake head and are growing leaves...note the differance towards the plant at the left that hasn't experanced this problem...
