Thin strapped dresses no good for school run though unless you like showing off your bra straps to the world or are brave enough to go braless in a thin strappy dress whilst juggling fractious children, sun hats, water bottles, bags and maybe wrestling a toddler or two.
A school run dress needs to be made of non-see-though fabric, have straps wide enough to hide bra straps, not be too short or too low-cut or too tight in the skirt for the inevitable bending down, and not be too giddy looking. It's an elusive creature...