Because swimwear is designed for the purpose of being outdoors, in water or is used to sunbathe. Different fabric.
Underthings, are not and clearly look like underthings.
Swimwear is not generally made of delicate lace-type fabric.
Underthings, are not and clearly look like underthings.
Swimwear is not generally made of delicate lace-type fabric.
Disclaimer: I am only responsible for what I say, not what you choose to understand.