Unless something is done to crack down on people who drop litter in the streets

[Nonverbis]

IELTS Advantage Writing Skills by Richard Brown and Lewis Richards

This was given in the answer key:

Unless something is done to crack down on people who drop litter in the streets, our urban environment will continue to be
dirty and full of rubbish.

Could you help me understayd why 'something' us used here. I have put anything.

Is my variant correct or not? In conditional clauses 'any' is supposed to be used.

 

[5jj]

In conditional clauses 'any' is supposed to be used.

Where did you hear that?

 

[Nonverbis]

Where did you hear that?

If I'm not mistaken, textbooks mention that in conditional sentences we use 'any'.

Example (English Grammar in Use by Raymond Murphy):

 

[5jj]

The book you quoted says that we often (my emphasis added) use any. We often don't, so it's not a very helpful 'rule'. Something is the natural choice in your original example.

 

[Nonverbis]

Something is the natural choice in your original example.

But how can I understand which choice is correct if there is no rule?

 

[5jj]

Some is used if the idea is restricted or limited in some way.
Any is used if the idea is unrestricted or unlimited.
Any applies to all or none; some applies to part.

The restriction may be a real one - There's some cheese in the fridge - or a psychological one existing only in the mind of the speaker - Would you like something to eat?

Lewis, Michael, 1986. The English Verb. Hove: LTP