Regardless of the goals of the organization, the ADA (and general decency/competency) gives the city a duty to affirmatively attempt to keep those curb cuts clear so that the disabled (or really anyone) can use them to access the sidewalk. When citizens do the work of finding where the cars are blocking them and then telling the appropriate authorities, who then can't be bothered to come out and even write a ticket, that's just sticking their finger in the eye of anyone who cares about citizens being able to get around the city safely. The city deserves to be sued in that case.