Outside China, companies and governments usually have to be careful when making investments. They can't decide to start building transmission lines/housing/fast train lines/deploy 5G everywhere and spend huge amounts of money if the return is small/non existent... And so usually things are only built or improved when there's a demand for it.
China can make a 5 year plan to build UHVDC everywhere and the grid operator won't go under no matter what. This has been working for them so far (even though it creates some serious problems) and certainly gives them an advantage, but you can't do that in most places.