The problem isn’t that trademarks are country-based but that trademarks are business area based. You can have multiple trademarks for the same word for different companies if the companies do different things. Apple doesn’t have the right to prevent you from using the word „apple“ to sell lawn mowers.
Should then only multi-national organisations be allowed to obtain gTLDs?
Obviously the ICANN price tag of USD227k is also a good entry barrier.