there are rotating outlets advertised in Home Depot's web site

No, the big advantage of wall warts is that the manufacturer can buy them with whatever compliance/safety certifications are necessary for the intended market and *greatly* simplify product compliance. It's still not free, but the difficulties are *greatly* reduced. The WWs spread these costs over kabillions of units.

Such wall warts already exist. They have replaceable prongs and are often sold with a kit for all major markets. We use this sort for our products that are sold internationally.

Intertek corporation's listing ID. One of UL's competitors.

They told you above; CSA.

When I hit the lotto and build my dream house, all the outlets will be quads, with extras on counters, and at desk and tv and bedwall locations. Always put extra outlets near the corners on bed walls- good builders do this as a matter of course, and often add (at owner's request) extra switches for ceiling light and fan.