why isn't it 叉子和勺子 or 叉和勺?
The sound for 人用 is missing and they should not be in one tile in the first place.
Much as there are differences between British and American English, in Taiwan 勺子 refers to a ladle or cooking spoon, while we eat with 湯匙 "soup spoons".
And we eat with a 调羹 never with a 勺子。 I am so confused as to how I should ask for a spoon now. Haha. Think I'll just stick to 调羹(tiáo gēng) because I hear it here more often. (Shanghai)
When is 子 required? Sometimes it's needed, and sometimes not, and I don't remember any explanation about when.