The thing is there have been loads of other alternatives over the years. Blackberry, WebOS, Windows Mobile, Tizen. Actual customers said no, these are what they want.

A lot of them faced what I would argue anti-competitive behaviour to prevent their growth.

For example, Google banning their apps on Windows Mobile and Amazon Firestore. Google blocking Windows Phone users from accessing maps/mail via a user-agent check. That and Google actively blocking Microsoft developing a native Youtube app.

Is it any surprise that customers were unsatisfied?

Apple and Google's duopoly is natural, no question about it. That doesn't mean we should ignore how they use it.

Google is rightfully scolded for requiring that users sign away their information and following their every move (often using dark patterns).

Apple should be put on hot coals too for how they are abusing their position. Spotify is an excellent illustration because Apple is both the platform and a competitor. I don't understand why an Apple consumer would support their anticompetitive stance.

As soon as you install some apps, your iPhone is tracking you as well. The recent stories about FourSquare have made me realize that things are much worse than I previously thought.

That's one reason I only keep essential apps ;) also use DNS blocking for trackers.

It's much better than Android even without that though. Especially since Google became more aggressive with tricking users to sign away their privacy.

There are lots of Android versions with all Google tracking code excised.

Are they sold like this directly from the manufacturer?

No, you just download them and install the new OS. Just like you have to jailbreak your iphone if you want to use it however you see fit.