The iPhone mini might be a counter-example. The iPhone mini has sold poorly and it seems like Apple is unlikely to continue it when they redesign the form factor. They'll keep it around while they keep this form factor since they've already spent the money, but I doubt that we'll see an iPhone 15 mini (when they're likely to come out with a redesign based on their 3-year cadence).
https://www.macrumors.com/2021/02/09/iphone-12-mini-low-janu...
https://www.macrumors.com/2021/02/15/iphone-13-mini-expected...
https://www.macrumors.com/2021/01/05/iphone-12-mini-sales-la...
https://www.macrumors.com/2021/01/22/poor-iphone-12-mini-sal...
https://www.macrumors.com/2021/06/30/apple-ends-iphone-12-mi...
> it seems that phone makers who usually copy Apple on everything, just skip this idea at all
Making a smaller device is difficult. You still have to pack in the same guts, but you have less space to do it. This is particularly acute when it comes to battery.
Android phones often need 50-100% more battery to achieve similar battery life as the iPhone.
https://www.anandtech.com/show/17004/apples-iphone-13-series...
Here we see an iPhone 13 Pro with 3095 mAh battery getting 16.62 hours of battery life. The Asus ROG Phone 5 gets 16 hours with a 6000 mAh battery. The Samsung Galaxy S21 Ultra gets 15.91 hours with a 5000 mAh battery.
Android phone manufacturers need space for large batteries. The iPhone mini's 2406 mAh battery is smaller than an iPhone Pro, but it's less than half what a lot of Android phones are coming with. Android phones seem to have standardized on 5000+ mAh and that's more than double an iPhone mini's battery.
Then there's also the heat/cooling situation. With a smaller space, it becomes harder to engineer.
And if they create this smaller phone which might be harder to make, would customers be willing to pay as much for it? I was kinda shocked that Apple offered the iPhone mini for $100 less than the regular iPhone.
When it comes down to it, the iPhone mini probably nets Apple 1-2% of its revenue. Is that enough to keep it around? Maybe. But Android manufacturers don't have Apple's margins and they don't have Apple's volume.
The reason there aren't Android mini phones is that customers don't buy mini phones. Even if they say that they'd like a mini phone, they aren't willing to buy it. Every woman I know says that mini phones would be the biggest seller. Apple has tried that and it's only 5%. I love my iPhone mini and I'll be really sad if Apple gets rid of it. I don't see why people want giant phones. At the same time, I understand the engineering challenges of smaller phones and acknowledge that while I think everyone should want a smaller phone, they don't.