Those two statements seem fairly contradictory to me. Like others, I was brought up to call strangers (and people older than me) by their surname unless invited to do so.

I'm frequently addressed as "sir" at a coffee shop, let alone when flying anything other than Y. The next step would be Mr. Estate, and finally by my first name.

Addressing someone by their surname doesn't mean you they're better than you, it's just a level of repsect that should be automatically afforded to a customer, especially someone who has paid a lot of money to be there. If you think calling someone sir or madam, or even by their title and surname makes them better than you, I suggest you try your hand at some form of hospitality work - you'll soon realise it's simply not how it works.

For the record: I often ask FAs to call me by my first name, but I greatly appreciate that they first address me by my surname.