Heavy school bags carried by children (a massive future problem!)

Can I ask how many other grandparents are worried about the weight of their grandchildren's backpacks they cart to and from school? And the toll it takes/will take on their backs in later life.
I've offered to buy my three a pilot type pull-along version so there is the option of using either method when appropriate. One grandchild has a long hill to climb and when I collet her I can barely carry hers it is so heavy what with her school computer and homework books. However a pull-along type is against her school's policy. At my grandson's school parents are obliged to buy the school's own backpack and a pull-along design is not a feature. He says he dreads sports days as the kit, football boots etc together with a computer and homework books, makes his load so heavy he's practically crippled. The teachers don't seem to be sympathetic. The other school children say the same. I wonder if we can get together and encourage secondary schools heads to change their minds and allow the short 'stick' pull-along backpack models? On Amazon they are under £50.