Why not? My local mexican place does interesting things with cacti, very tasty. If you've ever had sushi you've probably had seaweed..which is part of the algae family.
That's a dumb attitude. Cacti produce some amazing fruits that I bet even a simpleton like you would enjoy. I eat about 60% of this list on a weekly basis, so some countries (not America) do actually have access to healthy foods already.
I'm not a simpleton, I'm just not gullible enough to eat arbitrary exotic food reccommended by a big company when everything I need is in stores around me.
Canned nopal can be readily found at grocery stores around here (Chicago). I'm sure I could find algae easily enough if I tried...