Perhaps because software on its own is unlikely to hurt people, while we have seen plenty of physical products causing deaths and mutilation: Failing car breaks

Perhaps because software on its own is unlikely to hurt people, while we have seen plenty of physical products causing deaths and mutilation: Failing car breaks, cellphone batteries catching fire, strollers cutting off fingers, playground structures collapsing and so on. It only takes a few shitty products in a category for regulations to be set up