Also, the wings just have to support their own weight on the ground usually and not carry the whole aircraft around.
Well OK, about 5% of the weight is carried by the nose landing gear, and in some cases a bit more by a centreline gear, but if the main gear is mounted on the wings then the rest of the weight is supported by the main gear legs and that bending moment has to be carried by the wing root structure. Still a lot less than 3.75g acting out at 45% semispan though.