Apple is luxury big tech.

In this day and age, privacy is luxury, so that's what they sell.

I don't think there are any ethical motivations for them (or any other large corporation - none of them have morals so they cannot act morally). It's just that there's a market niche, so it will be filled by someone.

It’s an additional layer of wall for their walled garden to keep the technically proficient users that are more likely to hop walls.

money from advertising basically dwarf user lifetime purchase of privacy tax you mentioned