I agree it’s for Dominicans and the average literate Dominican should be able to do it without mistakes. But for example from my family in law, all well educated, I expect several to make some mistakes.
The fact that the test is relatively easy and shouldn’t cause a problem if you’re reasonably educated, doesn’t mean that in the Dominican reality of even smart educated people making simple spelling mistakes, a test like this doesn’t add value.
Another phenomen in DR is the rich locals are receiving bilingual education and often extended education abroad, their written Spanish isn’t always that good.