The measure is aimed at reducing accidents in urban areas with heavy pedestrian traffic and narrow streets, marking a major shift in the country’s traffic rules as these roads account for around 70% of all ordinary roads nationwide.
[…] above [30 kph] the risk of pedestrians suffering fatal injuries in accidents is said to spike.
[…]
The aim of the speed limit change “is to prevent accidents by stopping dangerous driving, such as failing to slow down even on busy streets”


That’s probably street design issue.