PHP and vulnerable example code is an additional thing. Most people just copypaste from tutorials. For example, the first search result for "PHP mysql example"

PHP and vulnerable example code is an additional thing. Most people just copypaste from tutorials. For example, the first search result for "PHP mysql example" gives you the wrong example first https://www.w3schools.com/php/php_mysql_select.asp https://www.w3schools.com/php/php_mysql_select.asp