But you can empty the trash and they can't build your apps.
Also, when thinking about creating value, you need to think about scale. They change your trash and are limited by their physical ability and time. Let's say they saved you 4 minutes and changed 400 trashes, saving 399 other people 4 minutes. They've created ~24 hours of value.
If your app helps people save 30 seconds a day and did that for 100k people, then you created about 12 days more value.
Your argument can easily go the other way. What if your app wastes 30 seconds a day for 100k people? By, say, building addictive mobile games, or a social network dedicated to watching food pictures, or gambling websites, or, like the parent comment said, throwaway apps.
Also, when thinking about creating value, you need to think about scale. They change your trash and are limited by their physical ability and time. Let's say they saved you 4 minutes and changed 400 trashes, saving 399 other people 4 minutes. They've created ~24 hours of value.
If your app helps people save 30 seconds a day and did that for 100k people, then you created about 12 days more value.