Preschoolers struggle with Scalar Implicature (SI) generation, showing difficulties in interpreting the scalar element “some” with its upper-bounded meaning “some but not all”. Strikingly, despite the fact that the comprehension of “some” is not adult-like until at least 5 years of age, recent corpus data suggest that children, in production, can use “some” as “not all” already in their third year of life. In this paper, we propose the Asymmetry Account, an account of SI generation formulated in the framework of Bidirectional Optimality Theory (Bi-OT). By taking Bi-OT as a model of language use, we show that the comprehension of “some” requires hearers’ to consider the speaker’s perspective, but not vice versa: to produce “some” with its upper-bounded meaning no mentalizing about other perspectives is needed. In light of this, we predict that the comprehension of weak scalar elements such as “some” is cognitively more demanding than their production and argue that children’s difficulty with the “some”-implicature is to be related to children’s developing of cognitive abilities, in particular, Theory of Mind.