Where I've worked for the last twenty years, we have a leave booking system and I have to put in a leave request and my manager has to approve/deny. I've been there through the phases of this being by paper form, by email, and now by online form with email confirmations.

It is a pretty big deal for leave requests to be denied, but it does occasionally happen, and I kind of eyebrow-raise at that "I've never denied an employee time off" - do you have no coverage clashes ever? (Flashback to the time my team had an interim manager who just approved everyone's leave bookings automatically, so the new manager came in to find we had no-one at all scheduled to work in the week before our Christmas shutdown - it's normally quiet that week, but we need at least one person available.)

But like, I don't "respectfully ask permission", I say "I'm booking this time off" and boss either clicks approve, or much more rarely has a conversation with me about why the dates I want are an issue, and we see if we can find a solution. That's not me being passive-aggressive, that's just me using my leave, which is part of my compensation for the job.