If you are arguing in favor of "local by default", there are strong arguments against this: http://lua-users.org/wiki/LocalByDefault
- local by default weakens what you can do with the scope;
- we want something by default because the language is used for things like configuration files.
The 2nd point means this must be valid:
param_1 = "foo"
param_2 = "bar"
What we do instead is use two kinds of tools: static global detectors and strictures (like in Perl). Similar tools are integrated in IDEs as well.
With these tools, I have never had an issue with scoping in code I have written. But it takes a little time to get used to it.
For sure. That ship has probably sailed. And, like you said, linters alleviate a lot of that pain. But that's a separate question from, "is this a good language feature?"