No apps => Nobody buys => No users => Nobody makes apps

I'd seriously consider if I at least got the bare necessities, like my bank.

Hardware is too locked down. Open source chip platforms are only starting to be developed now after decades of computing. It's all been running off the same architectures from monopolists. Linux phone devs like PostmarketOS work in such a tiny box that AOSP guys get much further. That is what I have gathered learning about it past few years anyways.

1. They're horrible

2. So you designed an OS, nice, so, the apps are vertical to match, right?... r-right?

Because they aren't fully baked and they aren't properly backed by billion/trillion dollar companies.

As many pointed out, lack of apps.

Don't know how much it improved over the years,
but battery life wasn't the best either.

What Linux mobile needs to gain traction imo,
would be Android app virtualisation.

Kinda like Waydroid, WSL, WSA, WinApps, WinBoat...
But then specifically for seamless Android apps on Linux mobile.

That could close the gap of lack of apps,
resulting in more users/devs,
resulting in more native apps,
eventually resulting in less need for Android apps on Linux mobile.

because phone manufacturers don't make them available without going through hoops.

Hardware support.

If I have to own a specific phone or line of phones, that I otherwise would never buy, I'm not going to get one just to run Linux on it.

For me, it's lack of Linux smartphones and also not selling in more popular shops. If I wasn't curious about Linux and decided to watch videos online about it, I wouldn't have known a Linux Smartphone exist and also, a smartphone is already a oversaturated market where it's just another iPhone or some sort of variation of a Android phone.

I'm sure what I'm about to say has already been echoed by others, but there are a few factors working against them. This is from a US/Canada perspective. Other countries may have more or fewer barriers.

1. Mobile hardware - Mobile hardware has higher security. Some of this is by design for the user, since mobile devices are more likely to fall into wrong hands than e.g. a desktop. Some of it is corps preventing users from using their hardware in ways they don't want you to, though. The level of locked down mobile hardware has only increased over time.
2. Carriers - This one is particular to North America, I think. Carriers here have a long history of meddling in phone hardware - from bloatware to SIM locks and everything in between. One of the things they do since LTE is require device makers to pay them to get certified to make calls on their network. Linux capable devices are too niche to be able to afford this. This is why Fairphone, for example, even with its Android-based OS, only works on one carrier here.

Those are the main two barriers here. Things like apps can have workarounds for those that would be interested in early adoption of Linux phones. But there's no way around the combination of carrier certification costs and limited options of only very locked down hardware.

It’s banking:

https://slrpnk.net/post/28294479

The army of corporate boot lickers in the mobile phone context is largely composed of people who think banking on a smartphone is wise, despite the attack surface and despite the bank being empowered to monitor their customers more closely. Banking apps are the most significant culprit for gluing people to Android.

We may never see the day when more than 5% of the population realises the importance of FOSS enough to shake free of their addiction to convenience.

A lot of technical answers, but consider a social driver: Linux users and developers are a lot more likely to prefer to do their computing on a "real" computer with a keyboard and large screen. Therefore, Linux as a desktop/laptop OS will always be significantly ahead of mobile offerings.

In my case it's because I can't get hardware that supports it without paying a fortune for importing. The other option is ancient hardware that most likely has a cooked battery that I'd have to hunt for in a used market.

Then there's the lack of VoLTE support on a lot of models which is becoming a non-starter as carriers are taking down the 3G towers.

That's before I've even gotten to try the software which I'm not hearing great things about.

It's not popular because it's an enthusiast niche at best. Linux mobile needs more time in the oven before it's ready, by my measurement another couple of decades.

My guess is that because hardware support, you can install PC Linux on pretty much any system, but I am unaware of mobile Linux os that officially supports my phone.

Because they don't work as phones, at least not for practical use

No one has cracked it yet, some projects seem to be getting close, but the radio in a phone is a very complicated and poorly documented black box

Every review I've seen of them is really bad. Basic things like simply placing or receiving a call do not work properly.

@ryujin470 Difference between ARM architectures, few standards, closed bootloaders, no interest for developing apps...

Android is Linux based and arguably the most popular mobile OS.

I'm still fucking pissed that MS stopped Windows Phone development. My Lumia 950XL was the height of my smartphone experience. Live tiles, so, like, I could just look at my home screen and see how my accounts were doing (yeah, I used to have savings and investments and such) alongside weather and ... a Jedi needs not these things.

But when you get laid off three times in a year, the calculus changes. "Sorry you're fucked, but we don't care" -- IRS

I wanted to try GrapheneOS on an old Pixel, but when I pulled it out of the box, the power button was gone. And you can't really fake it with a ballpoint pen.