I wouldn't stress too much about beans being in tacos, the amount that is mixed into a premade taco would be 1tbsp or less and that would be around 2.3g effective for refried beans (from Fitday), beans are moderately high in carbs but have also got a reasonable amount of fibre in them, unless you are in induction where you stay off the beans they are a great addition to a diet.

I add kidney beans to my chilli con carne, it ups the carbs a bit (1 cup has 39.94g carbs but 16.38g fibre making it 23.56g effective for a cup - my chilli con carne makes 8-10 servings so that adds about 2.9 - 2.3g carbs to each meal)

In my book they are a great food if you have the carb allowance available....

Fiona