I am against this for a number of reasons.
1, I had a child knowing the hours that school was open and planned my life/work around that. I want to spend time with my daughter after school, not get her home, shovel some food in and then send her to bed.
2, My child does a number of out of school activities, including 2 hours of tutoring per week. My dd has struggled at school and the tutoring has helped her where the school didn't/couldn't. if she has to be at school until 6pm she the tutor will have to be cancelled
3, When will children ever have time to have friends home to play? Social interaction is an important part of life
4, if the plans go ahead I will actually end up unemployed - I currently work for a company that gives tennis lessons to children after school - the majority of our coaching is between 4pm - 6pm, we would lose most of our clients and then I would lose my job.
5, If we bring in this rule our country will never produce a person that excels in any area of music or sport. Most professional sportsmen and musicians practiced several times a week as children - they won't have time to do this if they are in school until 6pm every day. Schools can not offer the expertise or facilities.
We are children for such a short part of our lives - our children should get the chance to be young and carefree, they should have the chance of fun activities and spare time - they are facing a lifetime of 40+ hour weeks and working until they are elderly.