I agree there's somewhat more trust involved, e.g. you don't know if they go to the park for the day and just check notifications on their phone, but you still have all the performance metrics to look at. If the person is doing all their work then it might be better to let them take that day at the park when they feel like it, especially if it's a salary position then you're more expected to do a certain amount of work then to be working a certain amount of hours.
Worst case you can always ask someone "hey can you show me what you did last week?" and it should be clear if someone isn't handling their responsibilities.