Why are there only three options to grant a child’s request for more time on their device?

Why does Apple only offer three options as options to grant a child more time on their device?

"15 minutes"

"1 hour"

"All Day"

Why can't it be a customised time (with the scrolling numbers) like when Screentime app limits are set up?

Is there a way around this?

Will Apple provide an update to allow this in the near future?