Isn't this a trivial example though? You require bucket size >= 10 say. Full on differential privacy is meant to address harder problems. For example, if you a

Isn't this a trivial example though? You require bucket size >= 10 say. Full on differential privacy is meant to address harder problems. For example, if you assume that there was a minor bug and people were asked to take the mandatory yearly survey again in a week. Now if you assume that the responses of people who responded before will stay the same when they re-respond, then by taking the difference between both results you can identify some specific people by looking at which bucket counts changed - this would be how the new guy who joined in that week voted. Differential privacy techniques are meant to anonymise data in way that you can't even do this.