They feed them the chicken starter and other feed designed for chickens without knowing they are essentially dooming their baby turkeys. Turkeys, because of their larger size, need a diet with much more protein than baby chicks.
Depending on where you live and where you are keeping your baby turkeys, if they get too cold they can easily die. Baby turkeys need time to develop the down necessary to keep them warm and protect them from the wind.
Just like keeping your baby turkeys too cold can accidentally kill them, keeping them too hot can be fatal as well. Some well-meaning owners pump the heat lamp way too high and end up overheating their turkeys.