No. They don’t and they wouldn’t.

None of this account for differences in purchasing power and phone price.

If you have an $150 Android device, I would of course expect you to spend way less on software than somebody with a $1500 iPhone.

I’m not saying ‘develop for Android only’ but if your business relies on one ecosystem only, you’re at a higher risk and you’re leaving money on the table.

Well, they have limited themselves to single point of failure.

That’s like selling only blue shoelaces and then crying faul when your only supplier stops making blue color.

If your livelihood depends on one account only, you are in great risk anyhow.

That sounds like anecdotal evidence. Android is more popular in more than half of the world and a lot of apps are successful and generate income on both platforms.

In all seriousness, I think I’ve seen ‘Mx’ used in this context.

Usually though, you’d go with a generic greeting such as ‘Dear Sir or Madam’ or ‘To whom it may concern’.