So what? Why should we as Americans consider it a taboo to ask people who look to be foreign and who hardly speak English to present proof of citizenship before we allow them to register to vote in our election? Don't we still require proof of citizenship (or at least a valid visa) to get driver's licenses, for example? Who cares what country they are from? Foreign nationals have no right to participate in American elections, period!
I suspect the problem was they were busy speaking in Amharic or possibly even Swahili ~ person to person ~ but that doesn't mean they don't know English.
A big part of the problem we've had integrating Somalian refugees is they come from two ends of society ~ primitive and urbane Westernized people. There doesn't seem to be an inbetween there.