You'd need two different SKUs for each different color and size to enable this in a more user-friendly way, where devices either enterprise locked or carrier locked get the one with a locked-by-default bootloader, and ones bought directly by the consumer have an unlocked bootloader. Realistically the latter group is so small it doesn't make sense to complicate the production and logistics process by having this separation. Instead, we get the current situation where the bootloader can be unlocked after initial setup check.