The examples you have given are dependent upon having users in the area (others date around you, others to do your tasks that live nearby, etc.). These startups find an initial group of users in localized markets before expanding to other locations, usually offering an option to be notified when there are enough users in your area for the launch. The userbase does not have to be huge, just enough to fine tune results and offer concrete data "We tested our dating app in Cambridge, MA and 25% of test users went on a date in the first month. Users tended to click on the interests section the most, so we made that the highlighted section of a profile..."