Idk what their source was but I think you should look for cheapest “possible” to do a fair comparison (cause obviously a certain shop can have super expensive wings). Near me lowest for wings will be 3-5€/kg, canned tuna starts from 8/kg when on discount, but also has like 30% of seed or olive oil in it (so actual tuna cost to the consumer is more like 12€/kg minimum) Chicken is definitely cheaper everywhere IME.

BTW I’m talking raw chicken wings…everything pre-cooked costs more