Hi @jerrym58,
If you compare the topography of Oklahoma and Puerto Rico you'll notice the huge difference. In the center of Puerto Rico covering mostly all the island there is a mountain range called the "Cordillera Central" with mountains exceeding the 4Kfeet, so GMRS being UHF will be greatly limited. Besides this, throughout all the North, there are many small limestone/calcium carbonate mountains, so overall Puerto Rico is a mountainous island being small in overall area. I believe this is the reason there's so many GMRS repeaters, more repeaters are needed to cover the same area compared to OK.
Hope this is somewhat helpful.
