I buy this lettuce at several New England grocery chains.
Some of this companies greenhouses are as far south as Texas.
The good thing is that fresh lettuce at the one in Loudon, NH is still growing 24/7 in the middle of January. I am sure it costs more money to grow it in NH in the winter than it does other times of the year. Especially when it is minus 10 degrees outside.
I still would rather buy that then some grown in Chile that time of the year.
I would love to buy such produce, but I am in California. The only greenhouse produce I have noticed are cucumbers, which I buy.