Should pornography be allowed to be displayed on billboards or in storefront windows? Is it the job of parents to cover their children's eyes as they stroll thr

Should pornography be allowed to be displayed on billboards or in storefront windows? Is it the job of parents to cover their children's eyes as they stroll through town? As a society we have (mostly) set limits on where pornography can be accessed. Adult shops have a proprietor who can shoo kids out. Is the www different from public streets?