Because roundabouts consume a lot more land and are not that much safer for pedestrians.
Roundabouts actually consume the same amount of land as an intersection of similar traffic, they're also self regulating and dont require power. They're also more efficient and help the flow of traffic, with a crossroad or traffic light, you can only be using a maximum of two lanes, with a roundabout you can use all four at once.
The drivers are busy looking for traffic going around the circle and not compelled by personal protection to look both ways like they are at intersections
But it seems that it requires a higher quality of driver than is typical of your area.
At a roundabout you look both ways as you would for any intersection, not just for pedestrians but because people dont follow the rules. Think of it this way, when you're turning right at a T junction, do you only look for traffic approaching from the left?