Because “double insulation” is much more common here and is deemed sufficient enough. A/Cs and fridges are usually the only appliances which needs a ground connection. For those, we have sockets that has a hidden screw-in ground tap.
I can still find unsafe/bothersome exceptions though. For example, a lot of rice cookers doesn’t really seem to be “double insulated” but they still have two-pronged plugs. Another is custom-built PCs. You basically need to strategically place your PC near a socket which you usually use for your A/C just to have that ground connection.
