Sounds great on paper.
Now, if I go get a burger from Burger King, well where TF do they get their lettuce from? Ask the cashier, they'll throw their hands up and say 'I don't fucking know'.
Ask them for a burger without lettuce, they'll just take an already made burger off the heat rack and take the lettuce off of it, still leaving a contaminated burger.
At least Taco Bell is trying to do the right healthy thing for now, no lettuce on their tacos for the time being.
But seriously, if I went to a Subway (ignoring but also observing their fake tuna scandal), if I asked them where they get their lettuce from, they'd probably tell me either they don't know, or aren't authorized to say.....