Boiled chicken eggs are where there is no, and if not a gourmet, when peeling eggs out, you will not distinguish the other American chicken eggs anywhere in Vietnam.
Am I having an aneurysm or is that first paragraph gibberish?
My guess is they're used in industrial kitchens when preparing lunch for lots of people. You know, the same people who have 10L of egg-whites in the walk-in cooler. I can't imagine regular people using them, they're definitely not available in shops.