[dcchambers]

Who is to say the developer would charge less? Let's say, for example, a company called ezpay charges $1 per transaction. If an IAP costs $10, the dev makes $7 off the user who buys via Apple, and $9 off the user that buys via ezpay API in the app. They could lower the ezpay price to $8 and still only make $7, but why bother?

[Gigachad]

Because another company will offer the same product for slightly cheaper now that their fees are lower.

Google One already charges you less if you subscribe via web or android. They just haven't been allowed to advertise this fact in the iOS app.