I touch a nerve? Good if you can't see in a window or showcase a sushi what that is telling you? Is telling you that this kind of food is not consumed or very popular here, like whale meat, kangaroo meat or dogs and cats meat as they are in some Asian countries.
The question of this trendier foot such as Sushi is a beauty, well here people is not very found of seafood (at least not in his raw format), seafood still popular but is not "that popular" for that kind of foot you have to go to countries in the pacific rim, Chile, Peru, Ecuador etc. They are super in preparing this kind of meals.
Food here, as you all now by now is mostly based on (boring) beef and also isn't sophisticated or exotic, most the dishes are of Italian or Spanish in origin in some degree and the rest of Europe chuck in, Japanese Asian food was unknown and not consumed until the arrival of new immigrates from Asian countries on the last 25 years because of this it has become most accepted and readily available but still far away from what you can find in Canada or USA because as I said immigration is much, much recently.
Now when you are asking for sushi or tortillas (by the way the only tortillas know here are made with beaten eggs, potato and onion, or beaten eggs and spinach) or some other exotic Asian, Mexican, central American, Middle East or Eskimo food sure you will have this kid of reaction from locals, fine if you are asking but when some are complaining, moaning, whining about this or that because I can fin this or that like they can do in USA or Canada, well I tell you again this is not USA nor Canada, here what you see is what you get, nothing more nothing less.
Regarding the Corn Tortillas you should be able to make them with "harina de maiz" (maize flour) I believe readily available in any shop or supermarket.
No offence was intended or implied, if you feel I have been an ars...e please accept my apologies it wasn't my intention.