This is the dark pattern of "upload everything and delete the local copies" laid bare.
This is possible to override, of course. But it's not the default, so only the most tech-savvy users make use of the settings that keep your videos and photos local.
All in service of getting you to pay for iCloud storage when your phone starts to contain more data than they offer for free (5GB, which is laughable in 2026).
My phone came with 256 gigabyte of storage.
One also has to wonder if people actually regularly go through thousands of pictures...
That 5GB basically means you get free backups of your iPhone.
For photos you need to upgrade.