I can buy board shorts for women here--they're sold more for people who are into paddling sports and stuff like that where you're in and out of the water, but I've seen women in them at the local pool too. I own a pair and would hate to swim laps in them, though--I wear them at the beach or for canoeing.
T-shirts are generally banned in the pool here for men and women unless they're rashguards that are meant for swimming use. I've never seen a man in the pool in a t-shirt and normal shorts, and any of the more serious swimmers are in either the brief-style swimsuits or the snug swim trunks. Maybe men around here are less modest or something, but the board shorts tend to mostly be on the young guys who think they look cool. Even then, the ones in better shape seem to tend toward the European-style snug shorts.