"tacos" are popular here, every supermarket has kits, taco bill [not bell] everywhere
but i once or twice ate in an actual mexican restaurant [low populous here] and it was nothing like the crunchy shell stuff
i have since researched, and what aussies think of as "mexican" is more california style [i can't point to that on a map, but know it is not in mexico]
later, i discovered "texmex", which is my favourite of the three
You nailed it, Doffy.
In the mid Atlantic and northeast regions, where I'm from, there's a pretty stiff definition of a taco.
Baked stiff corn flower tortilla, ground beef with taco seasoning, lettuce, tomato and Shredded cheese.
Traveling the country I've learned tacos in different regions are vastly different.
You have corn, rice and wheat shells in hard or soft shell... and more likely soft in most places.
Guacamole is a given in some areas you might have to request to be removed.
Chicken, beef (cubed), seafood and shrimp are common. Though pork can be found as well.
Onions and peppers are often cooked in with the meat.
Breakfast tacos can be found easily in TX.
I've even seen legitimate, non-English speaking Mexicans serving "tacos" on pita bread.
Tapatyped