I'd say that the Yemeni case numbers are actually much much higher. I can't image their testing regime to be comprehensive.
As for UAE - they are pretty strict on mask wearing and from my visits there over the last 18 months, pretty COVID safe aware in general. Added of course COVID doesn't like the heat. More than one expat there I have talked to believes the numbers to be much higher. They were also vaxing workers early on - just when Delta was getting a hold on things, courtesy of Europeans escaping the winter. Interestingly the UAE case / death ratio is pretty much the same for Spoiler's Qatar. One death for nearly 400 reported cases.