Why are you comparing Zaha's EPL only non-penalty goals with Son's goals in all comps? A bit apples and oranges...
Zaha
20/21: 9 non penalty goals / 2 assists
21/22: 9 non penalty goals / 1 assist
Total: 18 non penalty goals / 3 assists
Son
20/21: 16 non penalty goals / 10 assists
21/22: 23 non penalty goals / 7 assists
Total: 39 non penalty goals / 17 assists