Where is the ACLU in Chicago and DC gun fee cases?

The ACLU in Missouri is suing to stop a proposal that would require voter IDs. One of their arguments is that even though the IDs are given out for free initially, eventually people will be required to buy one. The ACLU states that this requirement for the law would "disenfranchise impoverished voters." Yet, the fee for these IDs that they eventually will have to get is small compared to the fees required to register handguns in Chicago or DC. So if the ACLU believes their claim about the voter IDs, why isn't the ACLU trying to protect "impoverished" citizens who are being denied their ability to defend themselves and their families in those cities?

By the way, since the voter IDs are initially given out for free, it seems like it will be years before there will be standing to bring this part of the ACLU case.