The H-2B visa has an interesting regulatory aspect in that only residents of certain countries are eligible to participate in the program.
This is unlike most other visas and the only things that are vaguely similar is the Visa Waiver Program countries whose citizens do not need to apply for a tourist visa like the B2 visa to enter the US and these days just have to register online prior to coming.
The Green Card Diversity Visa Lottery has a provision which excludes certain countries citizens from participating but that is really because the US already accepts a lot of those countries residents anyway.
Why this list exists as it stands are why so many countries are excluded from participating in this program when they can participate in similar programs like the J1 Visa Work & Travel and the J1 Visa Internship programs is a mystery to me.
Anyway below is the list of H2B visa eligible countries as designated by the Department of Homeland Security