You are confusing castes and "untouchables'; only the latter had a raw deal from all castes, perhaps because of the lowly professions they were engaged in. Unfortunately, those professions - manual scavenging - are still allowed to prevail (visit any big railway station). If these 'professions' are abolished and those currently engaged in them are compulsorily made to swith to more respectable jobs, untouchability will vanish, I suppose. Now, christians and muslims also have 'castes' or grades.
