Helmet rule

Why is it that various state governments, sometimes, feel that helmets are necessary for the public and sometimes otherwise? It is beyond doubt to any sane person that a helmet is very much essential to any 2- wheeler rider and more so for the pillion-rider. However, 'out of the blue' decisions are made to revoke a rule, which would definitely save the lives of many thereby creating confusion in the public's mind as to whether helmets are necessary at all.