We have done extensive user studies on productivity apps for employees, consumer and citizen apps, compared the results of our studies with similar ones conducted by Apple and Samsung. There is no room for doubt: Users prefer single purpose apps. Complexity is not appreciated by users. Martha McLean basically said it all 😉
There are striking practical advantages to users as well as the government agencies providing for them: It easier for the user to rate a single purpose app and comment and give valueable feedback on the respective app store, and similarly it is easier for the app developer to incorporate that feedback into the next update of the app quickly. You can update apps with low complexity much more often, and keep them fresher easier and sharply focussed on actual user needs.
Mobile apps are consumed in a different way than other applications, consequently the "rules" for mobile apps are just different than the well-known rules for websites, or for business software.
That said, cities (and for that matter other government agencies) may want to have a number of single purpose apps available to their users. Users will group apps according to their own preferences and categories, as Martha said.
Full disclosure: I am with SAP, a global software company catering to governments and to other businesses of all sizes. We help governments run better with mobility, analytics, in-memory computing, SaaS and - more traditional - business applications. We recommend to all agencies to go mobile, not only because it may be good business for us, but because it is actually good business for government. Mobility is not a one-app topic; we stress the strategic importance: Mobile apps extend the reach of government to places, situations and people that otherwise could not be reached at similarly low cost and efforts. That is true for reaching citizens, as well as own staff. Read more about how mobile helps government in my blogs here on govloop and on the SAP Community Network.