I couldn't access the DMV because they didn't have assisted doors. Can I sue for monetary damages?

You are absolutely right - it doesn't seem right.  But, it also doesn't seem as if you had any monetary damages.  However, there is a slight chance that, if there is a statute which requires the DMV to have handicapped accessible doors (which I don't know), it also might provide a remedy for a violation, i.e. it might say that any violator would have to pay a certain amount to anyone harmed by the failure to have the required doors.