So it's not 5% of the world, as has been brought up in other threads, 110V power is in a lot more places than just the US. It is a substantial part of the industrialized (power hungry users) world. It is not going away anytime soon/ever.
Even without the 110V power situation, they still have to make different plugs for around the world which is added cost/effort.
A global plug to rule them all isn't going to happen, even if it did you would have decades of adapters. My comment on the NEMA plug was it could be a solution, as it is the closest thing there is to an answer (some other parts of the world may have similar dual voltage plugs too). No one likes adapters. But no one likes not being able to buy something either. I have adapters for my tools from Europe, some of them I could cut the cords and replace the ends, but I don't want to do that, I'll take the adapter instead. But also I can't easily swap the receptacle on the CT, so there is little point.
Further people move, folks don't want to have to re-buy tools if they move, and scrap stuff. So having something locked into one country isn't exactly desirable. This is where computers are nice, move anyplace in the world, you just have to find the right cord as the Power Supplies are 100-250VAC 50/60Hz with a common plug on that end.