reason that a book for their level would use meals rather than dishes?
No, there is no reason at all, especially that in the exercise above the one with notorious pancake meal we can read the proper names for meals aka breakfast, lunch and dinner.
Imagine how confused the student gets when they first read that pancakes are a meal and then learns from the teacher that breakfast is also a meal. Then they are prone to imagine that Brits have pancakes or chicken and rice for breakfast.
That is why I consider the book messed up by British authors who don`t care about food like Poles/Polesses do.
that talks about dishes
BS. We don`t believe one word of you now.