You are misunderstanding how it would work. People would still be awake when it's light out and asleep when it's dark.
Instead of everywhere starting their workday at 9am UTC like you're imagining, London would start their workday at 9am UTC, New York would start their workday at 4am UTC, Los Angeles would start their workday at 1am UTC.
I would really like to see a comparison between this flat fee per "unit" (in this case users) model vs tiered pricing based on the number of these same "units", where the "unit" is one that will be predefined and remain mostly static.
So in this case, something like "$15 per user" vs "$39 for <= 3 users, $99 for <= 10 users, $249 for <= 30 users".
Instead of everywhere starting their workday at 9am UTC like you're imagining, London would start their workday at 9am UTC, New York would start their workday at 4am UTC, Los Angeles would start their workday at 1am UTC.