Interestingly, Netherland does not make it mandatory, and the government recently warned that in some circumstances, it might actually be more dangerous: https:

Interestingly, Netherland does not make it mandatory, and the government recently warned that in some circumstances, it might actually be more dangerous: https://www.nu.nl/binnenland/6180537/autodeur-met-verste-hand-openen-is-volgens-ministerie-soms-juist-gevaarlijker.html https://www.nu.nl/binnenland/6180537/autodeur-met-verste-han... (Dutch)