In every programming language there is a way to define variables even if they are called something else. Many languages start off with the assumption that they can automatically create variables without the programmer defining them. As soon as anyone works on a big program, they realise the sloppy approach of automatic variable creation produces programs containing errors that are extremely hard to find. You can then change your programming language to require explicit definition of variables and add code to detect incorrect use.
We always fall down the stairs when we go outside. Why do you suggest we fix the stairs?
Every time we serve puffer fish in our restaurant, customers die. Why should we change our menu?
How to you avoid the error alerts from Firefox?
How to you avoid the error alerts from Firebug?