I think the reason with the lettuce is because it is pre packaged, same as for subway. Salads are fine if made at home because you know its fresh but pre packaged listeria can grown in it.
I was wondering about the sauces, like the tartare, mayos at maccas? I've been staying away from them because you can't have raw egg during pregnancy and wasn't sure if they were egg free, does anyone know?

I eat Cheeseburgers and I eat a McChicken but I ask for no salad no mayo and put on my own mayo (the praise light one has no egg)