Worldwide there's an issue with regions being devoted to mainly a single crop intended to supply tens of millions across several cities, often overseas.
Good when it works, better have a backup alternative when that fails.
Carnarvon represent!
Lettuce likes some pretty specific conditions. If there's one area that's perfectly suited to growing lettuce with the minimum resources (fertiliser/water etc) then grow it there. Better than trying to grow it in the desert or somewhere much too cold.
If Australians go without lettuce for a month or so nobody is going to die. Eat rocket, spinach and cabbage instead.
There was big social media/news thing when KFC announced they were replacing lettuce with cabbage on their burgers.
A lot of unhappy campers there - tbh I think if they went further and made it a nice slaw with a sharp/tangy dressing then it'd be a massive improvement to their usual soggy, greasy chicken, and undercooked/limp chips (fries)